NEW YORK - Miguel Cotto battered Sergio Martinez for nine rounds to claim the World Boxing Council middleweight title and become Puerto Rico's first four-division champion.
Argentina's Martinez didn't answer the bell for the 10th round and referee Michael Griffin called a halt.
Cotto had set the tone early, sending the champion to the canvas three times in the first round before a sold-out crowd of 21,090 at Madison Square Garden.
The Puerto Rican improved to 39-4 with 32 wins inside the distance while southpaw Martinez fell to 51-3-2 with 28 knockouts.
All three judges had it scored 90-77 for Cotto through nine rounds. Cotto relentlessly pushed Martinez back throughout the bout, landing punches almost at will.
Cotto was credited with a fourth knockdown in round nine when Martinez's glove grazed the canvas.
"I think we passed the audition," Cotto's trainer Freddie Roach said of Cotto's devastating middleweight debut.
The 33-year-old added a middleweight title to belts earned at light-welterweight, welterweight and light-middleweight.
"I'm so proud of Miguel. He worked so hard in camp and deserved this historic victory. He was picture-perfect. He won every round. He didn't get hit with nothing. His defence was beautiful," Roach said.
"When he came back to the corner after every round, I kept saying the same thing to him: 'That round was better than the last.'"
As a proven drawing card - particularly in New York — Cotto got top billing even though Martinez was making the second defence of his belt.
Cotto wasted no time in living up to his marquee status, staggering Martinez early in the first with a left over the Argentine's low right then landing another left that knocked Martinez down.
A left-right dropped him a second time, and Martinez went down once more before the first round ended.
"I got hit with a right hand (in the first round) and I was cold," Martinez said. "I never recuperated after that."
By the sixth, Cotto was landing to Martinez's body and head, and in the seventh staggered him with a sharp left-right.
Cotto was in total control in the eighth, and in the ninth unleashed a series of combinations that had Martinez doubled-over, prompting Griffin to give the Argentine a standing eight-count.
Martinez rose from his stool when the bell rang for the 10th, but he didn't make it to the center of the ring before trainer Pablo Sarmiento told Griffin enough was enough.