By Jeff Labrecque
Updated September 18, 2011 at 04:43 PM EDT

Undefeated boxer Floyd Mayweather knocked out WBC welterwight champion Victor Ortiz in controversial fashion last night, throwing two mighty punches at a defenseless Ortiz after the champion had lowered his gloves following a pause in the fourth round. While boos rained down on Mayweather after the fight, he redirected his fury at Larry Merchant, HBO’s infamously meandering 80-year-old analyst, who persisted with questions about the fight’s climax that the new champ tried to sidestep. Finally, Mayweather exploded, “You never give me a fair shake. HBO needs to fire you. You don’t know sh– about boxing!”

Merchant shot back, “I wish I was 50 years younger and I’d kick your ass” before handlers separated the two men. Watch the exchange, courtesy of TMZ, below: