Timothy Bradley ended Manny Pacquiao's 15-fight winning streak with a stunning split decision victory, seizing the Filipino icon's World Boxing Organization welterweight title.
Judge Jerry Roth scored the bout 115-113 for Pacquiao, while C.J. Ross and Duane Ford both saw it 115-113 for Bradley, even though it appeared Pacquiao hurt Bradley throughout the fight -- particularly with his straight left hand.
Pacquiao fell to 54-4-2 with 38 wins inside the distance, suffering his first defeat since he dropped a 12-round unanimous decision to Erik Morales in March 2005.
Pacquiao, a world champion in eight weight classes who is reckoned the best pound-for-pound fighter in the world, said he thought he had done enough to win.
"Absolutely, yes," he said during a post-bout interview, to cheers from the crowd of 14,206 at the MGM Grand Garden Arena.
"I respect the decision, but 100 percent I believe I won the fight," he said.
Bradley, who improved to 29-0 with 12 wins inside the distance, said of his opponent: "He's a strong puncher, he rocked me a couple of times in the fight, but I held my ground and fought to the end. This is boxing.
"Every round was pretty close. Pacquiao won some of the early rounds. I controlled the later rounds with my jab."
Promoter Bob Arum called the decision "unfathomable" and "incomprehensible".
"I want to congratulate Tim Bradley, he's going to make a lot of money," Arum said. "But I want to say I have never been ashamed as much to be associated with the sport of boxing as I am tonight."
Bradley came out aggressive and got the better of the exchanges early in the first round before Pacquiao hurt the American with three straight lefts late in the round.
Pacquiao continued to get to Bradley, wobbling him with a straight left in the third round and also landing his left over Bradley's gloves.
Bradley stayed in front of him and kept punching but didn't appear to be hurting the champion.
"To be honest, I don't think he hurt me with one punch," Pacquiao said.
In the fourth Pacquiao hurt Bradley with a series of blows. After one exchange that included a left to Bradley's jaw the American stumbled back.
Pacquiao rocked Bradley with another left to the head in the fifth and in the sixth backed Bradley into the ropes, unleashing a barrage that included a strong right hook to the body.
A tenacious Bradley continued to challenge Pacquiao, and it was Bradley's work in the final three rounds that sealed it for the judges, even though by then he was complaining to his corner of pain in his right foot, which he had twisted in an earlier round.
Bradley appeared at the post-fight press conference in a wheelchair and said he had in fact injured both ankles, one, he thought, when he stepped on the foot of referee Robert Byrd.
He was to head to hospital for X-rays.
The announcement of the result was greeted by boos from the pro-Pacquiao crowd. Pacquiao's wife Jinkee and sons Manny jnr and Michael -- watching their father fight in Las Vegas for the first time -- looked stunned.
Pacquiao called the decision "amazing" but declined to criticize the decision of the judges, who are all from the United States.
The fighter earned a controversial majority decision of his own over Juan Manuel Marquez in November to keep his winning streak intact.
But Arum said Saturday's decision was more of a shocker than Pacquiao's narrow win over Marquez.
"It was close, everybody said it was close," Arum said of Pacquiao-Marquez. "This wasn't really a close fight."