By Jhonny Gonzalez

Villa Ballester, Buenos Aires, Argentina - WBA "regular" junior welterweight champion Marcos Maidana (31-2, 28KOs) knocked out Petr Petrov (29-2-2, 13KOs) in the fourth round of a one-sided contest.

Petrov was doing a lot of holding and surving very early on and continued the same tactics in the second round. Maidana started landing in the third and kept backing Petrov in the ropes to unload with combinations. Whenever Maidana got too close, Petrov held to get out of trouble.

At the start of the fourth, Maidana put Petrov down and had him ina brief moment of trouble. The Russian boxer recovered well and used his defense skills to prevent Maidana from doing more damage. But in the final thirty seconds, Maidana blasted Petrov with a series of punches against the ropes, to the head and body, and nearly lifted him off his feet when the challenger crumbled down to his knees. The ref began a count but saw Petrov was in bad shape and waved off the fight.