Floyd Mayweather Jr. got a head butt, a kiss and a hug from Victor Ortiz.
He responded with a right hand that ended a bizarre fight early.
Mayweather remained unbeaten and did it in emphatic fashion Saturday night, stopping Ortiz at 2:59 of the fourth round to take the welterweight title Ortiz brought into the ring.
The end came just as the two fighters emerged from a break, in which Ortiz had embraced Mayweather in the centre of the ring. As they broke, Mayweather shot out a left hand and followed it with a right that put Ortiz down in his corner.
Ortiz struggled to get up as referee Joe Cortez called an end to the fight.
"We touched gloves and we were back to fighting and then I threw the left and right hand after the break," Mayweather said. "In the ring you have to protect yourself at all times."
The round was already controversial, as Ortiz appeared to head butt Mayweather intentionally, leading Cortez to take a point away from him. After the head butt, Ortiz went to Mayweather and gave him a kiss on the cheek.
Seconds later they were in the centre of the ring ready to resume action when two punches ended it quickly.
"I took the break by the referee and I obeyed exactly as I was told," Ortiz said. "And then, boom, he blindsided me."
Mayweather was winning the fight through three rounds, dominating with speed and landing good right hands to the head of Ortiz. He won all three rounds on two ringside scorecards, and two of three on the third.
Ortiz picked up the pace in the fourth round, trying desperately to get inside Mayweather's vaunted defence. He did on occasion and was having a better round when, late in the round, he appeared to intentionally head butt Mayweather in frustration as the two fought in Mayweather's corner.
"He did something dirty when it was his corner who said I was dirty," Mayweather said. "But I won the fight.
Mayweather later engaged in a verbal confrontation with HBO announcer Larry Merchant, calling him a name at one point.
Ortiz said he had apologized to Mayweather for the head butt and was getting ready to resume fighting when he said Mayweather punched too quickly coming out of the break.
"There's two ways to look at it but as far as I was concerned I came here to entertain the fans and I think they were entertained," Ortiz said. "There was a miscommunication with the referee but nobody is perfect and this was a learning experience."
Mayweather remained unbeaten in 42 fights, scoring the knockout he had predicted. Ortiz, who lost his 147-pound title, fell to 29-3-2.