MONTREAL — Daniel Santos knocked out Joachim Alcine with a right-left combination 2:10 into the sixth round tonight to take his World Boxing Association light middleweight title.

The 32-year-old Santos (32-3-1), of Puerto Rico, had outboxed a nervous-looking Alcine (30-1), of Montreal, in three of the first five rounds.

In the sixth, the southpaw Santos threw a jab up the middle and then floored Alcine with a left hook. Alcine tried to get up, but fell back on his side before a stunned home crowd of more than 8,000 for the open-air bout at Uniprix Stadium.

Alcine won the WBA belt in July 2007 from American Travis Simms in Bridgeport, Conn., and made a successful optional defense in December against Alfonso Mosquera. This was his first mandatory defense.

Santos is a champion for the third time. He held the WBO welterweight title from 1999 to 2001 and the WBO light middleweight belt from 2002-05, finally losing it to Sergei Dzinziruk.

In the undercard, David Lemieux (9-0) of Montreal, the gifted 19-year-old who turned pro in 2007, knocked overmatched Oswaldo Gonzalez (1-8-1) of Mexico down three times before the bout was stopped at 1:53 of the second round of a light middleweight fight.

In another title bout, Alex Bunema (30-5-2) retained the minor WBA Intercontinental belt by stopping Walter Dario Matthysse (26-4) of Argentina with a knockdown at the end of the sixth round of a scheduled 12-round fight.

Heavyweight Bermane Stiverne (15-1), a Montreal native who fights for King out of Las Vegas, made short work of previous unbeaten American Brad Gregory (10-1), ending the scheduled eight-rounder with his second knockdown 2:35 into the first round. It was Stiverne's first fight in Montreal.

Montreal welterweight Benyamine Besmi (10-0) was flattened by a left in the first round but came back to stop Baltazar (Matamuchachos) Perez (3-3) of Mexico in the fifth round of a free-swinging bout, and Tony Luis (2-0) of Cornwall, Ont., won all four rounds handily against Jean Charlemange (10602) of Montreal.

The scheduled co-feature between light middleweight Phil Lo Greco (15-0) of Montreal and Alejandro Juarez (15-1-1) was canceled when the Mexican tested positive for Hepatitis C in a pre-fight blood test.