Ricardo Mayorga knocked down Fernando Vargas in the first and 11th rounds to capture a majority decision here on Friday in a duel of former world champions, sending Vargas to retirement in defeat.
Two judges scored the Nicaraguan fighter a winner by scores of 115-111 and 114-112 while the third saw the bout as a 113-113 draw.
Each man was at the heaviest size of his career in the super-middleweight matchup, but it was the focus and discipline Mayorga showed that surprised Vargas and allowed Mayorga to land knockdown blows late in rounds.
"In training I showed a lot more discipline and I was able to put it into practice," Mayorga said. "The style of fighting he came with, I didn't anticipate it, but I was able to change and come up with it."
Three-time world champion Mayorga, who last won 27 months ago, improved to 28-6 with one draw in his first fight since losing the World Boxing Council junior middleweight title 18 months ago to Oscar de la Hoya.
"It was a difficult thing to overcome the de la Hoya loss but I was able to come back with a big win," Mayorga said.
US two-time world champion Vargas, who turns 30 next month, fell to 26-5 and confirmed after the loss what he had said all along, that he was hanging up his gloves for the last time.
"This is my last fight. You don't want to have a bad night but sometimes it's just one of those nights," Vargas said.
"I thought he would be a lot more wilder. Unfortunately that wasn't the case. He was the better man."
Mayorga made his decisive second knockdown of Vargas in the last instant of the 11th round when he smashed a right hand into Vargas' face and sent him sprawling to the canvas on his rear.
Vargas, who also went down in round one, was kept on the defensive much of the 12th round even as Mayorga took moments to raise a hand in victory between exchanges.
"Those were just flash knockdowns," Vargas said, but added, "I don't want to take anything from Ricardo. He just got the better of me."
Mayorga went at Vargas with hard punches at the start, keeping Vargas on the defensive most of the first round, and the aggressiveness paid off when Mayorga knocked Vargas to the canvas with 20 seconds remaining in the first round.
A right uppercut stunned Vargas and he stumbled back and fell onto the canvas to give the Nicaraguan the early edge.
Another right by Mayorga midway into the second round buckled Vargas' knees and yet another right staggered Vargas again late in the round.
A Mayorga flurry pinned Vargas in a corner in the first minute of round three and opened a cut above Vargas' left eye but Vargas answered with a hard right and finally began landing his best punches in response.
Vargas was connecting with solid flurries in the sixth round but in the seventh Mayorga again struck with fury, replacing the antics of past fights with a determined attack.
Mayorga landed a hard right to Vargas' head well after the bell in the eighth round, one the Nicaraguan dominated, and Vargas responded with powerful punches in the ninth, taking the fight to Mayorga to set up the dramatic end.
Vargas was to have fought Mayorga in September but the fight was delayed because Vargas was anemic.