Pacquiao has now won five titles in five weight classes
Filipino superstar Manny Pacquiao became a five-weight, five-time world champion with a stunning victory over Miguel Cotto in Las Vegas.
Pacquiao stopped his Puerto Rican opponent in the 12th round of their WBO welterweight clash at the MGM Grand.
The 30-year-old dominated throughout and had his opponent down in the third and fourth rounds with his speed and accuracy proving too much for Cotto.
Referee Kenny Bayless stopped the fight 55 seconds into the final round.
"I tried my best to knock him out," Pacquiao said.
"I thought in 11th round they would stop the fight. I am surprised he continued to fight."
Cotto's face was swollen, blood was flowing from his nose and his cuts, and he simply could not stop Pacquiao from bouncing inside and throwing both hands at will.
"I didn't know from where the punches were coming," Cotto said.
"Manny Pacquiao is one of the best boxers I ever fought."
Pacquiao's victory sees him confirm his status as the world's best pound-for-pound boxer and takes his record to 50 wins, three defeats and two draws with 38 knockouts.
Some ring observers believe Pacquiao has now won world titles in seven weight divisions, a boxing record, but only five of his title wins came in fights sanctioned by one of boxing's four major bodies - the WBC, WBO, IBF and WBA.
The victory over 29-year-old Cotto sets up the possibility of a mouth-watering clash with unbeaten Floyd Mayweather Jr.
And Pacquiao's trainer Freddie Roach admitted after the fight that he would like to see his man take on the American in a fight that would have global appeal.
Cotto began the contest strongly behind a stiff left jab as the pair traded punches in an explosive start to the fight.
Pacquiao could now face Floyd Mayweather Jr.
Pacquiao soon found his range and took control dropping Cotto with a right hand early in the third round. But Cotto showed he wasn't badly hurt and came back with a strong finish to the round.
But after Pacquiao put Cotto on the canvas with a big left hand as the Puerto Rican was advancing forward late in the fourth round, the 29-year-old was never the same again.
Cotto fought gamely but in the later rounds he was just trying to survive as blood flowed down his face and Pacquiao kept coming after him relentlessly.
But Cotto refused to quit even as his corner tried to throw in the towel after the 11th but after sustaining yet more punishment in the final round, the fight was called to a halt.
"I heard that he was bigger than me and stronger than me and that's why I tried to be more aggressive and fight toe to toe and try to (negate) his power," said Pacquiao.
"Our strategy for the fight was not to hurry, take our time, because we knew his strategy was that he was going to counter."
This is the last weight division for me. It's history for me and more importantly a Filipino did it
Cotto, whose record now stands at 34-2, was taken to hospital following the fight with his face swollen and bloodied.
"My health comes first. I just want to make sure I'm fine, but I feel great. I'm swollen but that's all," Cotto said.
Having now won at welterweight Pacquiao said he would not move up in weight any more.
"This is the last weight division for me," Pacquiao said.
"It's history for me and more importantly a Filipino did it."
"I thought we could break him down and if Manny put pressure on him he could get him out of there and he finally did," added Roach.
"Early in the fight he was tested with Miguel's power and laying on the ropes a little too much but once he got his rhythm on the fight it was all over."