David Haye retained his WBA heavyweight title with a third-round stoppage against Audley Harrison in Manchester.Harrison crumbled under a barrage of blows as the all-British showdown came to life after a tentative opening two rounds where few punches were thrown.Haye, 30, waited for his chance and was clinical when it arrived, flooring his 39-year-old fellow Londoner.Former Olympic champion Harrison, 39, had said it was his destiny to triumph, but landed just one significant punch.The fight had been marketed as 'The Best of Enemies' as the two former friends met in the biggest heavyweight clash in British boxing since Lennox Lewis beat Frank Bruno in 1993.However Harrison, who has been criticised for failing to build on the promise of his gold at the Sydney Games in 2000, was nervy and offered little resistance before the fight was halted one minute 53 seconds into the third round."I'm very happy with it. I said to people close to me I would stop him in three rounds and that's exactly what I did," said Haye."I put a lot of money on the third round and lot of my friends and family did. I didn't want to let them down by doing him too early." The beaten older man Harrison, nicknamed 'A-Force', was downbeat and claimed the referee stopped the fight prematurely.When asked if he would now retire, he replied: "I've got to sit down and reflect."Harrison boasted a three-stone weight advantage and a two-and-a-half-inch height difference, but Haye's slimmed-down frame enhanced his superior speed.A boisterous 20,000 sell-out crowd at the MEN Arena booed Harrison into the ring and the jeers continued in a tame opening round, with Harrison offering three southpaw jabs to Haye's solitary body shot and occasional probing.Referee Luis Pabon called the fighters together to urge them to fight during the second round, though Haye at least landed a hard right early on and two more later in the session before the fight exploded in the third.Haye jumped in with a right hand and hurt Harrison. With Harrison on the ropes he followed it with a left-right combination which rocked the challenger's head back.Further attacks to the body followed before he focused on the head once more, unleashing left hooks and straight rights which sent his man to the floor.Harrison was back on his feet on the count of eight but Haye ran across the ring to finish him off with a huge roundhouse right and the referee called a halt.