Updated

Floyd Mayweather Jr. won his 42nd straight added the WBC welterweight title to his ledger with a fourth- view card at the MGM Grand.

The end came shortly after Ortiz had lost a point for a flagrant head butt when he backed Mayweather into a corner. As if to apologize, Ortiz actually leaned in to kiss Mayweather on the cheek while being given the point deduction.

After the fighters were waved back together, referee Joe Cortez looked toward the scorer's table. Just before the action started, Ortiz dropped his hands around Mayweather's waist and stepped back for a split second, and was instantly hit with a left hook. Ortiz looked at Cortez, but at the same time was then pounded with a straight right that sent him down for the 10 count. Ortiz was counted out with one second left in the round.

Mayweather then had a profanity-laced verbal confrontation with HBO's Larry Merchant during the post-fight interview, during which Mayweather said fighters should "protect yourself at all times." Mayweather complained that he never receives a "fair shake" from the reporter. Mayweather said Merchant "doesn't know (expletive) about boxing." At the end of the interview, the 80- year-old Merchant said he wished he was 50 years younger and he'd kick Mayweather's (rear).

The 34-year-old Mayweather (42-0, 26 KOs), a Michigan native now based in Las Vegas, hadn't fought since beating Shane Mosley at the same venue on May 1, 2010.

Ortiz (29-3-2), a former prospect at 140 pounds, won his title at 147 with a 12-round defeat of Andre Berto.