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ALL THE LATEST ACTION (all times GMT)
0300: Thank you all. It was short and sweet. But Haye announced his world credentials this evening and America (the reason we're all up so late) will certainly have taken notice. Well done to the Haymaker and hard luck to Big Mac. I'm sure we'll see much more of both of them soon.
In Haye, we may well have been watching a future heavyweight champion of the world. Here's hoping...
"I'm Welsh and gutted, but glad I didn't pay 15 quid to watch 5 mins of catastrophe!"Anonymous via text on 81111
Your man took a beating. That's true. But he is still a great champion and will be back. By his own admission, he made a mistake and paid with his WBO title.
"Well done Hayemaker. Done England proud. Good luck in Heavyweight."Dixie, Stoke via text on 81111
"Superb win for Haye. What a finish that was. Fantastic."Umar, London via text on 81111
0234: We said this could be over quickly. It was. Awesome from Haye and the official timing of the win was by stoppage after two minutes and four seconds of the second round.
Round two: There is plenty on the table - the WBC, WBA and WBO cruiserweight belts to be precise - and Haye sets out his stall to take it all. Two huge right hands stagger Maccarinelli and he follows up with a sensational combination in the corner. It's all over. Brilliant by Haye. He is the undisputed champion.
Round one: After all the hype, the first 90 seconds are super cagey. But a couple of fizzing punches thrown by each man remind us of the power on display in there. A late Haye combo half makes contact, but nothing decisive.
0224: The referee is John Keane from Northampton. And Joe Calzaghe is standing by his man Macca in the ring as the announcements are made. Haye is pacing like a caged animal now. It's fight time!
"It's rocking now and the roof will blow off the O2 when Maccarinelli wins in round 9."
BBC Sport's Ben Dirs at ringsideSo Ben has pinned his flag to the mask. I have no idea, but I'll go the other way. Haye in five. But it's a toss-up.
0220: Maccarinelli comes out in a black hood. He sprints into the ring. Ladies and gentlemen, we are moments away.
0217: Jimmy Lennon Jr is the Master of Ceremonies and he introduces our two fighters. Haye is out first and he still looks as cool as a cucumber. Big reception for the local boy.
"Anyone else think this is a crazy time for an all British fight?
Asad Saeed, Cardiff via text on 81111
"We're at a wedding disco with Frank Bruno and Evander Holyfield."
Carrie at the O2 via text
0212: The O2 has gone into party mode and a few literal big hitters are at ringside, including messrs Bruno, Holyfield and Khan.
0205: Haye is looking super composed in his dressing room as he gets taped up. Is he too loose though? It's a criticism that he has faced before but somehow I doubt that he will come out undercooked tonight. Not a chance.
"Evander is in the house and he evidently has absolutely no idea who Amir Khan is. Big Frank gets a bigger cheer than the Real Deal though. What a fight that might have been..."
BBC Sport's Ben Dirs at ringside
0151: After much talk of an 0300 start, it seems that Haye v Macca is almost upon us. Buckle up. Just to remind you, these two have 48 wins and 40 KOs between them and just two losses. Expect fireworks from the start and refresh this page often. This may not last very long.
0146: That was a breathtaking fight from the super featherweights. Next up it's the big men. And I can hardly wait.
"Didn't see that coming! Mitchell looked almost as if in a daze for four or five rounds and Johanneson seemed far stronger, but one shot is all it takes to make a boxing writer look silly."
BBC Sport's Ben Dirs at ringside
0131: Great round for Mitchell, who puts Johanneson on the floor. He follows up and the referee steps in. Super finish from Mitchell, who was made to work very hard for that. He showed brilliant resilience there because he had a dodgy spell in the middle of this fight.
0128: Mitchell has plenty of heart. He has been rocked to the boots a couple of times but is still standing and banging with Johanneson, who seems to be the stronger man at the moment. Eight rounds in the book and this is very close on points. As a reminder to those bleary-eyed Brits who are joining this commentary late. This is the last fight on the undercard before Macca v Haye. And a little beauty of a fight it is too.
0120: Mitchell is hanging on. That was a big sixth round for Johanneson, who is unlucky not to score a knockdown when his opponent briefly brushes the canvas.
0117: Belting fifth round. The better punches are Johanneson's.
0112: Johanneson is getting into his fight with Mitchell. Good fourth round. It could go either way. Which is pretty much how the public view Macca v Haye. Haye is a slender favourite, but I'm yet to hear a boxing expert who is 100% convinced who will prevail. That's what makes this a special night for British boxing.
"Can't wait, but I think it goes the distance - Enzo by decision."
Dean from Melksham via text on 81111
0100: Mitchell works the harder in round one and is very much on the front foot, but he gets caught with a couple as well. Interesting opening. And Amir Khan - a possible Mitchell opponent one day - is a very interested spectator at ringside.
"Mitchell v Johanneson could be wilder than the main event. This will not go the distance."
Paul via text
0052: Warm reception for Mitchell, luke warm for Johanneson, who is not quite as showy as his opponent tonight. Both are tough as nails though. This should be a belter.
"We've seen as many fights in the crowd as we have in the ring."
Micah via text
0045: Before the main event, the largely-patient crowd has a rather nice appetiser to feast on. Commonwealth super-featherweight champion Kevin Mitchell is up against British champ Carl Johanneson. There is no love lost there and it promises to be a suitably sparky prelude to Haye v Macca.
"The O2 is pretty much full and the general lethargy is starting to give way to nervous anticipation as the big fight draws near. Gazzetta dello Sport has even got a reporter ringside, presumably because of Enzo Macca's Italian connection. Being an Italian paper, she's wearing a black mini-dress and looks like Sophia Loren (sic)"
BBC Sport's Ben Dirs at ringside
"It's gonna be immense. The beers are chilled and it's almost here! Enzo to take it inside 4 rounds. Enjoy fight fans!"
Jamesie in Lancaster via text on 81111
0030: Best guess on fight time is somewhere between 0230 and 0300 but no-one is quite sure. One thing is for certain, the atmosphere at a packed O2 Arena is quite tasty. A full house of 14,000-odd fans and a few lagers have been had in the long wait for the main event. In case you were wondering, first bell is so late because of the US market. The plan is to launch both of these fighters as major world stars by exposing them to the money men across the Pond.
0020: Good morning fight fans and welcome to our build-up to one of the most mouth-watering domestic dust-ups of all-time. David Haye v Enzo Maccarinelli. England v Wales. Puncher v puncher. Hold on to your hats. This could be explosive and, once the fight eventually starts, quick.