Antonio Tarver has won the WBC light heavyweight title from Roy Jones Jr after the referee stopped the fight in the second round.
Jones Jr failed to recover after being floored
Tarver had got off to a slow start before catching Jones flush on the side of the face with a left hand.
Jones fell onto the ropes but recovered only to stumble across the ring and see the fight halted by referee Jay Nady halfway through the second round.
It was only the second defeat of Jones' 15-year professional career.
It was also only the second time the American, in his 25th world title fight, had been knocked down during that time.
The pair had met once before - in November last year - when Jones was given a victory many thought Tarver deserved.
"I never gave up on my dream so here we are," said Tarver. "We both threw at the same time and I beat him to the punch. Right on the kisser."
A shocked Jones said: "I got no excuses. It happens like that sometimes. I
am having a hard time getting up to fight guys."
On the undercard, Zab Judah (31-2, 22 KOs) claimed the WBO's number one welterweight spot with a tough split decision over Rafael "Derby" Pineda (38-6, 31 KOs).
Judah, fighting just five weeks after losing to undisputed champion Cory Spinks, dropped Pineda in round seven but the 38-year-old came storming back in the later rounds and the judges scored it 115-112 Judah, 114-113 Judah and 115-112 for Pineda.
IBF light flyweight champion Victor Burgos (37-13-3, 22 KOs) floored former two-time world champion Fahlan Sakkreerin twice en route to a sixth round stoppage.