A bloodied Juan Manuel Marquez rallied to knock out eight division champ Manny Pacquiao with one second left in the sixth round to win the fourth fight of their epic boxing rivalry.
The 39-year-old Marquez, who suffered a broken nose and possible concussion, Saturday 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 the hospital after the fight for repairs.
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, who admitted he went into the fight "over-confident" and got "careless", 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.
Pacquiao, who was a 3/1 on ($1.33) favourite on Friday, dropped to 54-5-2 with 38 knockouts. Pacquiao weighed in at the division's 147-pound limit (66.67kg) while Marquez, who improved to 55-6-1 with 40 knockouts, came in at 143 pounds (64.86kg).
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.
Indeed, Pacquiao kept coming and Marquez appeared to be heading to his third defeat to Pacquiao after Marquez was bloodied and knocked down in the fifth.
Pacquiao came out attacking from the opening bell throwing lefts over the top of Marquez's gloves.
Pacquiao was the aggressor early, landing a solid left halfway through the second that jolted Marquez.
By the time the sixth round started Marquez looked a bloody mess, bleeding from a cut over his nose and from the mouth.
Both the third and fourth rounds ended with the boxers slugging it out in the centre of the ring.
"After the first knockdown Manny came back and he was in charge," said Pacquiao's trainer Freddie Roach. "But he got a little too careless."