Luis Collazo stopped Victor Ortiz with one punch at 2:59 of the second round Saturday at Barclays Center in Brooklyn, N.Y.

The second round was about to come to an end when Ortiz, in the process of unloading a right, was caught with a hard right hook to the jaw. Collazo (35-5, 18 knockouts) landed two more grazing shots as Ortiz went down, obviously hurt.

Referee Benji Esteves reached the count of 10 and Ortiz, on his knees, was unable to get up.

The victory over a world-class opponent was the most significant step in Collazo’s comeback after two long breaks from the sport. The Brooklyn native held the WBA welterweight title back in 2005-06.

Ortiz (29-5-2, 22 KOs) was returning to the ring after a 19-month layoff. His most-recent fight, against Josesito Lopez in June of 2012, was stopped because Ortiz suffered a broken jaw. He has now lost three consecutive fights.

Saturday’s fight was close through one-plus round, although Ortiz fought somewhat wildly.  Collazo, a veteran, fought with more patience and precision.

A full report will follow shortly.