- Associated Press - Sunday, September 18, 2011

LAS VEGAS — Floyd Mayweather Jr. remained unbeaten Saturday night by knocking out Victor Ortiz with a right hand late in the fourth round.

The punch came just after the two fighters had hugged in the middle of the ring after a head butt by Ortiz clearly irritated Mayweather. As they separated, Mayweather shot out a right hand that put Ortiz on the canvas, and he was counted out as he struggled to get up.

It was a wild end to a fight that Mayweather was dominating until Ortiz seemed to intentionally head butt him in the corner. After referee Joe Cortez took away a point and separated them, the two met in the center of the ring to resume action.

After a brief embrace, Mayweather shot out a left, then a right that put Ortiz down.

It was the 42nd straight win for Mayweather as a pro.