Japanese MotoGP rider Daijiro Kato died on Saturday from injuries sustained in the Japan Grand Prix.
The 26-year-old Honda rider was thrown off his bike after hitting a tyre barrier at Suzuka on 6 April.
The Japanese star won the 250cc world championship in 2001, and set records for most wins in a season (11) and the highest points total in the class.
He leaves a wife and two children.
This debate is now closed. A selection of your tributes appears below.
Watching Kato race was always a pleasure. He was fast and intuitive and his unique style and character, both on and off circuit, will be sorely missed. Our thoughts are with his family and friends.
You will be missed but never forgotten - a true champion in the heart of every real motorsport fan.
Amber Harwood-Payne, London, England
Kato was set to challenge for the 500 title within the next two years. This alone is a testament to his ability and character in the company of the world's very best.
David Hunter, Lexington, KY USA
Kato will live forever in the dreams of every young moto GP driver, most of all he will live on through the people who loved him. We'll miss you Daijiro.
What was billed as one the best GP seasons for some time has been sadly overshadowed by the loss of Kato-san. His skills on a bike were apparent for all to see when he was racing.
He is a big loss to bike racing and will be sorely missed by fellow racers and fans alike. My thoughts are well and truly with his family at this sad time.
Our thoughts are with his wife and children. He was an outstanding rider.
Phil & Sharon, Surrey UK
I am so sorry you are gone. We'll never forget you. Sleep peacefully
Lee Martinson, Caerphilly
Kato-san you will be greatly missed. The Motobike world has lost a true champion. I know the MotoGP world will do you proud by keeping your memory alive. Thank you for years of wonderful racing.
May you rest in peace
Victoria & Richard, Leeds
Peter Akinwunmi, Essex, UK
A Kato follower for the past three years and wearing his helmet with pride. God bless Daijiro's family and help them through this sad time. GP Sunday will never be the same again.
Jo Wilby, Sutton,Surrey
Thank you Kato-san for some marvellous racing. We always watched for you and will miss you greatly. May you rest in peace.
Glyn & Monica Wells,
Condolences to our champ's family & friends.
You may be gone, but never forgotten Kato san. May you rest in peace. Your wife and children should be proud of you always...xx
Victoria & Richard, Leeds
I am sad and mad. Why no red flag? Why no medical assistance at the scene without manhandling Daijiro on to a stretcher from the track, just so the race could continue?
A great distress to have lost a terrific rider in Daijiro
But overriding I am saddened. I used to laugh along with Toby Moody as Kato would prove an accomplished adversary with the line shouted 'Not now Kato!' as he would begin to slice through the pack so precisely.
Hardly putting his wheels out of alignment on his 250cc he reminded me of Harada, smooth and extremely fast. He often had a small gonk on the starting grid and would be smiling and joking. New viewers would not have see this side of him as the homerace pressure was on at Suzuka.
I hope the BBC will do Daijiro the justice of covering any moment of silence at the South African race this weekend.
A great distress to have lost a terrific rider in Daijiro. The bike racing community will mourn his departure. All thoughts are with his family. Thank you for your memories over the years. Goodbye to my champion. God bless.
Kato, God bless you and your family, I will miss you.
Miss you Daijiro, love Domnall aged six.
Daijiro.... we are saddened by your passing but your achievements will live on. Our thoughts are with the Kato and Honda families.
Stewart Curran, Amsterdam
It will be painful to watch the grid form up without him this weekend
He was a great rider. Given more time he could have become champion. The best Japanese MotoGP star will definitely be missed.
Liam O'Donnell, Gloucster
Because of his lost future, there will be a missing part in MotoGP history. I just wish to have a look at Dai's 74 back on the track once more. He was our hero, is always and will be forever. Rest in peace.
Sayonara Kato San.
Just simply a legend.
He was pure class; two years ago, I think everyone was a little shocked at the way he destroyed the opposition in the 250s. He was definitely expected to be the first Japanese World Champion in the blue riband class of motorsport.
He's going to be missed and it will be painful to watch the grid form up without him at Welkom this weekend.
The death of a truly magnificent racer and humble man. He will be sadly missed. Deepest sympathy to his family. Rest in peace Daijiro. We shall not forget you.
A world champion lost forever. My thoughts go out to Daijiro's family, friends and also the Movistar Honda team. We shall dearly miss him
C Swann, East Sussex
Kato was an inspiration to everyone around him
I don't follow MotoGP but I feel very sorry for Kato's family and his friends. It's always horrifying too see a driver dying when doing his job. Riding a motorcycle is always dangerous and sadly we have got an example again. Rest in peace Daijiro.
Ride the wind Katosan.
Kato was an inspiration to everyone around him. He was the great champion. He was too young to die and my thoughts and prayers are with his children and wife.
Dan Fletcher, Chicago U.S.A
My thoughts go out to Daijiro's family and friends. In my opinion a future world champion in the MotoGP class, such a great loss to the sport, where he had so much more to give.
Sean Poynter, Hertford
You will be missed.
Some people are truly amazing, they risk their lives to entertain us, to provide for their families and to push further the boundaries of human endeavours; Daijiro Kato was one of them. May God's blessings and presence be with his wife and kids.
I do miss Daijiro very, very much. He was a super nice
person, all Japanese MotoGP fans loved him. It's still very sad
and all I can do is pray for Dai-chan and his family.
Have a good ride up there Kato!
My last child of three was born 13 months ago, and if it was going to be a boy, I wanted to call him after Daijiro, but we had a girl. But I think this let's you know what a great racer and champion I think you were. God bless you, our hero.
Peter Collins, Mayenne, France
Have a good ride up there Kato!
Katosan, respect is due to a great rider. All who know of you mourn your loss, and we all send our heartfelt sadness to your wife and two little ones. Suzuka, Do the right thing!
Motor racing will always be dangerous, and we all know that. But still, it's so hard to accept that you are gone. There will not be another Daijiro Kato. You were very special. We will NEVER forget you Dai-chan. R.I.P
As a lifelong fan of motorcycle racing, it causes me great sadness to see a star like Kato-San taken from us. But as a husband and father, my strongest emotion is heartbreak on behalf of his young family, of whom he was so proud. There will be more great motorcyclists, but no-one will replace the father that those children have lost. I wish them peace at this terrible time.
Keith Elliott, Dublin, Ireland
It's always a sad thing to lose a racing hero while their doing the thing they do best, right there on the track. The motorsports world will never forget him. He was a champion, and he died as a champion. I give my sympathy to his family. May he rest in peace. Sayonara Daijiro Kato.
Muhd Shafeez Shaharan, Malaysia
A good man. Sadly missed. My thoughts are with his wife and new child. God bless Daijiro.
He was a racer who had a gift for speed.
This gift will be remembered along with him.
I was shocked to see the news what a sad loss it will be to the world of motoGP.
Neil Robinson, Amsterdam
A loss to bikers all over the world
You will be missed. All my sympathy to his family. Rest in peace,Daijiro. We will never forget you.
May you ride forever! Godspeed Daijiro.
I'll never forget you...thank you very much.
Kato...you were a great rider...the world cannot replace you. We all will sadly miss you Kato. Rest in peace.
Tributes from Sweden to one of the greatest racers ever lived. May he rest in peace.
Daijiro Kato. A loss to bikers all over the world.
My thoughts are with his wife and children.
Daijiro Kato will be remembered by myself for his non-stop aggressive style and his never give up attitude, a fine example to any young rider, and a massive talent that leaves a big void.
Alan Gibson, UK
The motorcycle world was deprived of one of the few men who could challenge Rossi's supremacy this season and in the years to come.
I think he had the talent to become Japan's first motoGP world champ.
I was saddened to hear the news of Daijiro's death whilst watching the British Superbikes on Sunday. He was a great rider and sportsman and will be sadly missed; our thoughts are with his family at this difficult time.
Josie Overton, Essex
It's sad that such a talented rising star had to die to prove the dangers of this track. He will be sadly missed
Valentino Rossi said earlier that the curve, where Kato had his accident, was too dangerous? So why didn't the organisers do anything about it?
John Drogan, Ramsbottom
A great talent to be lost so young. Sincere and best wishes to his very young family, our thoughts are with you.
Brian Jones, England.
Bike racing has lost another one of its finest. Kato was one of the best GP racers to watch, his 250cc races were always good to watch. My thoughts go out to his family. Rest in peace.
Kato-sama died doing what he loved so much and in what he was great at. Even though this can't be any consolation for his family and friends, whose pain we outsiders can't understand. Hopefully Kato's death will make the organisers more cautious and make them listen to the opinions or suggestions of those, who know the best, what is too dangerous: that is, the racers themselves.
Valentino Rossi said earlier that the curve, where Kato had his accident, was too dangerous? So why didn't the organisers do anything about it? Why did a great racer have to die because of it?
Everyone mentions we have lost a future world champion. He was the world champion in the 250cc class, and with a little more experience, the next threat to Valentino Rossi's domination. The greatest champion to come from Japan in any motorsport, he shall be sorely missed.
Yatin Chachad, South Bend, USA
A gentleman racer who had so much more to show the world. You will be missed.
I don't believe it. I will never forget your spiritual riding. Dai's soul will be eternal... sayonara.
Daijiro was a MotoGP champion in waiting. The best of him was still to come. This is a great loss for bike racing.
Daijiro Kato passing away will leave a huge hole in the MotoGP line-up
James Marshall, Bexley, Kent
The authorities must do what ever they cab to find the cause of this tragic event and improve safety at Suzuka and other circuits.
My deepest sympathy to the family, friends and team mates of Daijiro.
Paul Byrne, Manchester. UK
How sad it is to see that Daijiro Kato is no longer with us. Motorcycle racers are, in my opinion, the bravest sportsmen of them all.
They constantly risk life and limb to do the sport they love and should receive all the accolades they deserve and more some.
That was maybe the worst day in the history world motorcycling. We can't forget the thing he did. It is very sad, that he can't do it again. We all will miss him.
Prague - Czech Republic
Daijiro Kato passing away will leave a huge hole in the MotoGP line-up. He was a great rider who could have won the title in the not too distant future. My thoughts go out to his family, friends and team mates. He will be sorely missed by everyone.
James Marshall, Bexley, Kent
The loss of a rider of Daijiro Kato's calibre leaves the sport diminished. He will be missed. He runs the race now where the rubber side is always down and the weather is always perfect, Godspeed. Strength and love to his family and know we think of you...
Chip Syle, Harrisburg PA USA
Daijiro was the greatest rider Japan ever had
These guys know the risks, and they still race! They are true heroes who bring joy to millions.
Adrian Evans, West Bromwich
I don't know what to say, stunned by the death of a future 500 GP champion. Our thoughts are with his wife, children and family. May he rest in peace.
Ray, Buckinghamshire England
It's the biggest loss for Japanese motorcycle scene. Daijiro was the greatest rider Japan ever had. Rest in peace, Dai-chan! I will never forget you.
Toshiaki Takeuchi, US
We all know he was set to become Japan's first MotoGP champion sooner or later, and although he can't officially anymore, he'll be remembered as a champion in the hearts of his fans. Rest in peace.
Lee Gibson, Birmingham
His passing is a great loss to MotorGP. However, he will be remembered as a racing legend! Our deepest sympathy to his family.
More precautions must be taken
One of the brightest talents I have ever seen race and he will be missed. How can you sum up something like this in mere words? My thoughts are with his family.
Stephen Wagstaff, Dunstable, Beds, England
Daijiro Kato was a true racer; he had talent and determination few in GP racing possess. The grid will not be the same without him.
It's a sad day for Motorsport indeed. Kato has shown us Asian that you are what you do not what you look like. He has shown great courage and passion for his love of motorbikes and he will always be remembered as a great rider and a great man. Rest in peace warrior Daijiro Kato.
Mohd Shahrul Nizam, Malaysia
How many more deaths? Two years ago two drivers were killed in Nascar. With the technology at its immense speed all the sponsors want is to get their drivers going faster. Nobody cares about their safety. This won't be the last victim of this 'sport'.
More precautions must be taken. We have a choice; is human life or sponsors' gain is more important? That is the question we must answer.
Ogun Eratalay, Turkey
My thoughts are with his wife and especially his two young children. They'll never know the great man and rider their father was. Rest in peace Kato-san.
Rob, Edmonton, Canada
He was peerless in 2001 and should have gone on to be Japan's first MotoGP world champion
We've been robbed of a future world champion. I send sincere condolences to the family and friends of Daijiro Kato.
Neil Robertson, Cheltenham, UK
Daijiro-san was a real hero in the world. Rest in peace. I will never forget you. Thank you and goodbye. Ciao Daijiro, Ciao...
This is a great shock and loss. I watched the race and have been hoping and praying that he would be fine; little did I know God had other plans for him. He WAS one of my great riders; I just hope he has gone to a better place. Condolences to his loved ones.
Such a shock to lose such a talent. He was peerless in 2001 and should have gone on to be Japan's first MotoGP world champion. Our thoughts are with his wife and young family.
Daijiro was one of the young breed of Japanese riders who, after his 11 wins in a season, became my hero. I was hoping he would challenge Rossi and rewrite the history books for Asian riders in the MotoGP.
We will miss him, but not as much as his family do
Daijiro, rest in peace. My deepest sympathy to his wife and children.
Racing is taking risks,
but his battle was wanted by nobody.
Henry de Kuijer,
A tragic end to a brilliant, young talent. He'll be sorely missed.
Ben, Leicester, UK
Kato-san always had an ethereal quality about him. His dominance of the 250cc class was absolute. We will miss him, but not as much as his family do. Our grief should be lightened knowing he died carrying out the sport that he loved.
Kato will be missed by the world of motorsport and everyone I know. I had always followed his career in MotoGP because he is an inspiration to me and others. Goodbye Daijiro I will miss you and I will never forget you.
Matt Wilkinson, Warminster, England
It's a tragic day for the motorcycle sport; Daijiro was a strong personality, and will forever be remembered. RIP Daijiro.
Pierre B, Sweden
Kato was a great guy and a talented rider, he will be missed an awful lot in motorsport.
Karl Wilson, Desborough, Northants
It's sad to see the loss of this great rider; my thoughts go to his family and the team. The competitive world of MotoGP will feel this loss.
Kato's riding was a pleasure to watch
John Edwards & Roberta Kawasaki, Vancouver, Canada
Kato had great talent, he was most certainly a serious contender for this years GP championship. He will be sadly missed, my heart goes to his wife and family.
So sad, such an exciting rider. My thoughts go to his family.
Eileen, Wales, UK
Kato's riding was a pleasure to watch - he will be missed by all motorcycle fans in the world!
John Edwards & Roberta Kawasaki, Vancouver, Canada
Sadly, we'll never see just how good he was
We will miss a great champion and rider - rest in peace. Our thoughts are with your family. You will always be remembered, Kato.
David Clarke, March
What a brilliant talent, what a waste. Thanks for the memories Daijiro. Deepest sympethies to his family.
Baz Ball, Conisbrough, S.Yorks
The death of a second world championship rider in such a short period, one who had finished his racing career and another who had hardly started - both will be sadly missed. All our thoughts should go to the family, and respect their wishes.
Ian, West Mids. UK
I watched the race and saw how Kato was lifted from the track - if there were medics on the scene, I think they should be struck off and never allowed to cover a race again, not even a three-legged one.
My deepest sympathy to Kato's family and friends. His 2001 season is testimony to what should have been a fantastic future so sadly cut short.
Kato was a genuine talent. I was really looking forward to seeing how he would compete with Rossi, Biaggi and the likes in the 500s. Sympathies to his family and the team.
A great talent, will be sorely missed. Sadly, we'll never see just how good he was; his 250 title showed us he could rewrite the record books, and now we'll never know. Sympathies to his family, and RIP Kato-san.
Mike Wicks, Scotland
My heart goes out to his wife and kids
This guy was incredible. The skill involved to win a world championship in the 250cc class is amazing but to win that many races in the process just adds to the legend of Daijiro Kato.
It was great last season when he got his RCV Honda and his performances during the final races of 2002 were top notch. I will always remember him as the small bloke with the big bike. My heart goes out to his wife and kids.
Kato was one of the best Japanese riders, and I believed he would be even better and faster. However, I can't still believe he was so fast that he left all of us here.
I just wish Dai-chan rests in peace. I would like to convey my condolences to his family, especially his daughter Rinka-chan, who was born only 10 days before her dad's fatal accident.
To the family and friends of Kato, my deepest sympathy. A shining star has left us. God Speed Daijiro.
Jimmy Duggan, Boston USA
He has gone with honour for him self and his family! Fans around the world will remember him. All my sympathy to his family, friends and team.
He was a truly inspirational racer who could never be replaced
My deepest sympathy to Daijiro Kato's wife and family.
He was a terrific racer and his skills and determination to win races will be sorely missed.
My thoughts are with Kato's family and friends. I can't begin to imagine what they are going through
I would like to take the opportunity to convey my condolences to the family of Daijiro Kato, the Moto GP's will never be the same without him. He was a truly inspirational racer who could never be replaced.
Darryl Scott, Exeter, UK
He has gone with honour for himself and his family. Fans around the world will remember him. All my sympathy to his family, friends and team.
Kato was the equivalent to Gilles Villenueve of Formula One. Both of them raced with passion and determination.
Ronnie M, India
Kato will be sadly missed by everyone. He was a great champion - words can not replace a great person.
He was a good driver who aoculd have challenged for the championship. I feel sorry for such a good driver to die at a young age like this.
I send my sympathy to his family
Danny, Singapore, Bishan
My deepest sympathy to his family and friends. Kato was the brightest rider to come out of Asia and promised so much, yet he has been taken away from us too early. I hope Kato's death is not in vain and would at least hope it will inspire further Asian riders to shine just like he did.
The sport of MotoGP has lost a talented young man this weekend. Since his accident fans around the world have been hoping for his recovery, and we are saddened at his loss. I hope that the dangerous area at Suzuka, where Kato-san met with his accident, will be made safer for riders in future.
Also, when such a serious accident occurs the race should be stopped immediately so that the rider can receive medical attention at the site of the accident. We'll miss you, Kato-san.
Helen Munro, Singapore
I send my sympathy to his family. Kato was a great rider and was probably going to be a future world champion.