LAS VEGAS: A bloodied Juan Manuel Marquez rallied to knock out eight division champion Manny Pacquiao with one second left in the sixth round on Saturday to win the fourth fight of their epic rivalry.
The 39-year-old Mexican, who suffered a broken nose and possible concussion, sent Pacquiao face first to the canvas, giving him his first victory over the Filipino superstar.
''I got hit with a punch I didn't see,'' Pacquiao said.
Marquez knocked Pacquiao down in the third round then ended the fight with a overhand right that hit the advancing Pacquiao flush, sending him down hard.
Pacquiao, who suffered his second consecutive loss, landed under the ropes and lay there for a couple of minutes before getting up and returning to his corner.
Pacquiao was taken to hospital.
The shocking ending stunned the crowd of 16,348 at the MGM Grand Garden arena as Marquez had held his own in their first three fights but had never knocked down Pacquiao until Saturday night.
''I was going to retire last year. Now I feel great that I leave no doubt in the way I got this victory over Manny,'' Marquez said. ''I was counter-punching him. I got under his guard, threw the right hand when he tried to punch me.''
Pacquiao said he would like to fight Marquez again. ''I am going to rest and come back to fight. I would go for a fifth,'' he said.
The fighters set a blistering pace, making it look unlikely this fight would go the distance as their three previous fights had.
Pacquiao was eager to redeem himself after suffering a controversial defeat in his most recent fight to Tim Bradley. He was also tired of Marquez blaming his failure to win in their three previous fights on biased judging. Marquez claims he won all three earlier fights - although two were scored in favour of Pacquiao and one ended in a draw.
This time, four division champion Marquez left no doubt, showing he was willing to go toe-to-toe with Pacquiao even after getting knocked down in the fifth round. He had knocked Pacquiao down for the first time in 39 rounds between them in the third with a right hook over the top. ''It was a good shot, but I was able to come back,'' Pacquiao said of the third-round knockdown.
Meanwhile, former Cuban Olympic gold medallist Yuriorkis Gamboa won his fight on the undercard, giving rapper 50 Cent a victory in his debut as a boxing promoter.
Gamboa, fighting for the first time in more than a year, survived a ninth-round knockdown to take a unanimous 12-round decision over Michael Farenas of the Philippines in the 130-pound fight.
It was the first fight for Gamboa (22-0) with 50 Cent, who got his Nevada promoter's licence last month. The rapper reportedly paid $US1 million ($953,000) for the contract to promote Gamboa, who knocked down Farenas in the second and seventh rounds.