Floyd Mayweather came out on top in the richest fight in boxing history by defeating Oscar de la Hoya on a split decision after 12 rounds in Las Vegas.
Mayweather (left) took control in the final stages
In an absorbing rather than classic fight, the judges went for Mayweather's speed and crisper punching over De la Hoya's come-forward aggression.
Mayweather, who took De la Hoya's WBC light middleweight crown, won 116-112, 115-113, 113-115 on the scorecards.
Unbeaten Mayweather, 30, later reiterated his intention to retire.
"He threw a lot of punches but they weren't landing," said Mayweather, who was fighting at the 154lb limit for the first time and who has now won world titles at five weights.
"It was a hell of a fight but it was easy work for me. I out-punched him, I out-boxed him. He was rough, he was tough, but he couldn't beat me.
"I could see the shots coming. I stayed on the outside and made him miss. He's the best fighter of our era and I beat him.
I am the champion and you've got to do more than that to beat the champion
"Now I'm going to retire. I don't have anything left to prove, I have made a ton of money from this sport and I want to spend more time with my children."
De la Hoya, who hinted he could also now retire, countered: "I thought I landed crisper punches.
"If I didn't press the fight there would be no fight. I hurt him with a few punches that I know he felt.
"I was pressing and wanted to stop him. I was trying to close the show. I am the champion and you've got to do more than that to beat the champion."
Mayweather was roundly booed as he entered the arena accompanied by hip-hop star 50 Cent, who rapped all the way to the centre of the ring.
De la Hoya, on the other hand, was given a rapturous welcome, and it was he who came out of the blocks the fastest.
The 34-year-old ploughed forward in the first few rounds, backing Mayweather up with some heavy combinations to the body.
Magic Johnson and Jack Nicholson were at ringside
Indeed, a tentative Mayweather looked vulnerable for perhaps the first time in his career, and for a moment it looked as if he might be overpowered.
However, Mayweather, who struggled to penetrate De la Hoya's guard in the early exchanges, came to life in the fifth, making De la Hoya's knees sag with a crisp right-hand counter.
De la Hoya landed with a flurry of body blows in the sixth, although Mayweather was scoring all the time with pot-shots from range.
The next four rounds followed a similar pattern, with De la Hoya pressing and throwing occasional flurries and Mayweather landing with cleaner and cleaner shots.
But it was down the stretch that the fight was won, Mayweather upping his work-rate as the champion almost ground to a halt.
Mayweather looked to hurt De la Hoya with a big right hand with 20 seconds of the fight remaining and both fighters were swinging wildly when the final bell came.
Unsurprisingly, there was controversy after the bell, with concerns that the judges might have awarded the fight to Mayweather by mistake.
The cards mistakenly listed Mayweather fighting out of the red corner and De la Hoya out of the blue.
While the Nevada State Athletic Commission will study the matter, there appeared to be no grounds for a reversal.
The fight, which was seen in 176 countries, set a record for the biggest live gate at £9.6m and was expected to surpass the record 2m pay-per-view sales set by Mike Tyson-Evander Holyfield II in 1997.
Mayweather is now unbeaten in 38 professional encounters, while De la Hoya, a six-weight world champion, fell to 38 wins and five losses.