Andy Lee fought back from a first-round knockdown to beat John Jackson and claim the vacant NABF light middleweight title at Madison Square Garden.
Jackson, from the US Virgin Islands, had the Limerick man on the canvas in the opening round and had the better of the following three rounds as well.
Lee was behind on the scorecard before landing a killer right hook in the fifth round that dropped Jackson with the referee stopping the bout immediately.
Meanwhile, Miguel Cotto used a furious start to win the World Boxing Council middleweight championship as title holder Sergio Martinez of Argentina surrendered the crown when he did not answer the bell for the 10th round on Saturday.
Cotto, with a ferocious left hook and punishing combinations, knocked Martinez down three times in the first round, and continued to dominate the scheduled 12-round bout at Madison Square Garden.
Martinez's corner waved an end to the fight as the bell rang for round 10.