Miguel Cotto made history in New York as he claimed the WBC middleweight belt by emphatically dethroning Sergio Martinez at Madison Square Garden.
Cotto became the first boxer from Puerto Rico to win world titles at four different weights when Martinez failed to answer the bell for the start of the 10th round.
The Argentine's corner waved the fight off knowing he was a long, long way behind on the scorecards, particularly after he suffered the worst possible start to the contest.
In action for the first time since successfully defending the WBC strap against Englishman Martin Murray last April, Martinez was knocked down three times in a quite sensational opening round.
Cotto targeted the body as he threatened to make it an extremely early finish, though in the end he had to settle for a 10-6 round that gave him a healthy lead on the scorecards.
He continued to build on it as the bout wore on, Martinez - who needed knee surgery after his triumph over Murray in his home country - never appearing to threaten a comeback.
The 39-year-old was put down again in the ninth, the referee awarding it a knockdown despite the struggling champion not actually touching the canvas.
Still, the big left that did the damage was enough for Martinez's corner to take the decision to pull their man out and spare him from taking any further punishment.
I got hit and I never recovered after that. I tried my best, said Martinez, speaking through a translator, afterwards. He caught me cold, he caught me hard at the beginning and I didn't recover from it.
Cotto had previously been a world champion at light-welterweight, welterweight and light-middleweight. He now has a 39-4 record after his first outing at the 160lb limit.
This is the biggest achievement I ever had in my career, he said after becoming the first man to beat Martinez since Paul Williams in 2009. It was a reflection of my hard work (for) 10, 11 weeks.
His trainer, Freddie Roach, was also delighted at the 33-year-old's performance, insisting 'Junito' had followed the pre-fight plan laid out in their gym sessions to absolute perfection.
I'm really proud of him, he said. We had a great game plan and he followed it to a tee. He had him moving into the hook all night long. Miguel is a better boxer than Martinez.