Pacquiao dominated the fight's eight rounds to win by technical knockout
Manny Pacquiao dominated Oscar de la Hoya from the start to win Saturday's welterweight super-fight in Las Vegas.
The Filipino gave his bigger, more famous opponent such a beating that De la Hoya declined to come out of his corner after the eighth round.
The technical knockout marked only the second time De la Hoya had been stopped in his 16-year professional career.
"He's just a great fighter," said De la Hoya. "I have nothing bad to say about him. He prepared like a true champion."
Defeat for the 35-year-old came at the hands of a fighter who fought at just 129lb months earlier.
Speed was going to be the key to this fight. I prepared well to control the fight from the beginning
"Speed was going to be the key to this fight," said the victorious Pacquiao, 29, who picked up an $11m (£7.5m) purse.
"I'm not surprised by the result, because I prepared well to control the fight from the beginning. I'm happy that I could give this victory to my country."
De la Hoya seemed well beyond his prime, unable to offer any answer to the punches Pacquiao landed almost at will.
His left eye was closed as he sat on his stool after the eighth round and the ring doctor, referee and his cornermen discussed his condition.
The former six-weight world champion offered no complaints when his corner decided he had had enough, getting up from his stool and walking to the centre of the ring to congratulate Pacquiao.
"I felt empty, without power," said De la Hoya. "I tried to go forward but Pacquiao's leg speed and movement didn't allow me to connect with anything."
Two of the three ringside judges scored all eight rounds for Pacquiao, while a third gave De la Hoya - who was taken to a hospital for precautionary reasons after the fight - only the first round.
I just don't have it any more. My heart still wants to fight, but when you physically can't respond, what can you do?
Pacquiao (48-3-2, 36 knockouts) came up two weight classes to fight for his biggest purse ever, while De la Hoya was having his first fight at 147lb in seven years.
Though De la Hoya (39-6) towered over Pacquiao and had a big reach advantage, Pacquiao had no trouble getting inside what few jabs the American threw to land his shots.
"We knew we had him after the first round," said Pacquiao's trainer, Freddie Roach, who also handles Britain's Amir Khan.
"He had no legs, he was hesitant and he was shot."
Roach trained De la Hoya in his last big fight a year ago and said his former charge could no longer throw punches when he needed them.
"Freddie, you're right," De la Hoya told his former trainer after the fight.
"I just don't have it any more. My heart still wants to fight, that's for sure.
"But when you physically can't respond, what can you do? I have to be smart and make sure I think about my future plans."
Pacquiao's victory sets up a potential clash with Manchester's light-welterweight king Ricky Hatton next summer, although Floyd Mayweather Jr may also be tempted to come out of retirement to face him.
"I know Ray Hatton," said Pacquiao's promoter Bob Arum. "We'll sit down, we'll talk, that's probably the most logical fight to be made - Manny against Ricky Hatton at 140lb.
"Obviously Manny would want to fight at 140 and so would Ricky. That's probably number one on the drawing board. But let the kid have a great Christmas and New Year, then we'll sit down to business."
Hatton, ringside for the fight, said: "Manny's proved again that he's pound-for-pound the number one in the sport and I still might get my dream of becoming the best pound-for-pound fighter in the world."