Sergio Martinez overcame a brave performance from Martin Murray to retain his WBC middleweight belt on points in Buenos Aires and bring an end the Englishman's unbeaten record.
Martinez (51-2-2), backed by a crowd of more than 40,000 inside the Estadio Jose Amalfitani, was floored by the St Helens fighter in the eighth round but got up and secured a narrow points margin on all three judges' cards.
Murray started brightly, landing a series of crisp shots that seemed to trouble the 38-year-old, but Martinez overcame his early frustrations and edged the opening rounds with the British fighter sitting back too often after catching his opponent.
By the midway point of the fifth round Martinez was bleeding from his left eye after a couple of decent straight shots from Murray, but that sparked the Argentinian fighter into action with some eye-catching work.
With the fight still up for grabs, Murray upped his attack in the eighth and shortly after landing a left-hook, a back-pedalling Martinez hit the canvas when he was caught with another solid right.
Martinez bloodied Murray's nose in the ninth, but there was controversy in the 10th when the home hero went down again under punches in a neutral corner, only to have it ruled a slip by referee Massimo Barrovecchio - wet conditions had left ring conditions very greasy.
An anxious home crowd roared their champion on over the remaining two rounds, and the Martinez response probably sealed his victory as he denied Murray the chance to make his mark with the judges and secure a big finish.
All three ringside judges gave the victory to Martinez with identical 115-112 scorelines, with Murray crediting Martinez for winning 'fair and square' and admitting periods of the fight when he had been too passive had cost him victory.