|Esther's mental battle to stay top|
|Around the Academy:
Esther Vergeer is the most famous disabled sportsperson in Holland.
Forget Roger Federer, when it comes to wheelchair tennis the 23-year-old is a dominant force.
She has been the world number one for four years during which time she has won four Paralympic gold medals.
She says: "Before the 2004 Paralympics 7% of Dutch people knew who I was and after it is now 33%.
"The 2004 Paralympics were something I had been working towards and winning a gold medal, any medal, is like a dream come true.
"Even though I won gold in Sydney 2000 and Athens, the motivation is still there to do the same in Beijing in 2008.
"At the moment I can earn a living from tennis so it would be stupid to quit now."
But when you win everything there is to play for, does winning become a bit boring?
Esther says: "I think it's good for wheelchair tennis in general that I lose some matches over the next couple of years.
"There are lots of younger girls coming up, especially from Holland, so I'm really looking forward to more competition.
"But I'm not the kind of person that likes to lose!
"When I lost to Daniela Di Toro last year in Sydney I didn't prepare as good as I normally do.
"So that kept me focussed and I told myself: 'Well if you want to win you just have to work for it'.
"Usually I train three or four times a week doing tennis which lasts about two or three hours.
"Then I'll go to the gym twice a week for two hours each time. Once a week I do conditional training for an hour and then I'll do some exercises on my hand bike at home where I work out a little more on my arms and my abs."
Surprisingly for someone who is far and away the best on tour, the rewards in wheelchair tennis can sometimes barely cover the air fare.
Esther says: "I have several sponsors and that's how I earn my money. The prize money on the ITF Tour is not that big. The winner's cheque for a Grand Slam is usually between $1500 and $2000.
"Sometimes I feel guilty because I feel like I steal the sponsors away from the other wheelchair tennis players in Holland.
"But on the other hand if they work hard or they win big tournaments and work hard on their own PR then it's possible that they can get sponsors too."
A difficult choice
Esther has been in a wheelchair since she was nine years old. An operation to relieve a brain haemorrhage left her legs unable to move.
Part of her rehabilitation programme involved playing sports but it wasn't just tennis that Esther was good at.
She says: "I could have played basketball professionally and it was a very tough decision to choose between the two when I was 17.
"Basketball and tennis are such different sports so it's hard to compare them.
"What I liked about basketball is that whenever you train or play you are always so tired and exhausted because the physical part is harder than in tennis.
"I liked that and the team part as well.
"But playing tennis is an individual sport and my trainer said that I could be number one, I could go to the Paralympics, I could earn some money and travel all around the world.
"Those challenges were bigger than the team player part. It was a hard decision but I've never regretted it."