Chad Dawson took the World Boxing Council light heavyweight crown from veteran Bernard Hopkins with a majority decision at the Boardwalk Hall arena.
Dawson improved to 31-1 with 17 knockouts as he won the rematch of their controversial clash in Los Angeles in October by scores of 117-111 on two of the judges' scorecards. The third judge scored it even, 114-114.
"I feel great," Dawson said. "I took a lot of head-butts. My head is hurting right now.
"He is a great fighter and he is going into the Hall of Fame. But I stepped my game up another notch."
The biggest question now for the 47-year-old Hopkins is if this marked the final fight of his career.
Hopkins' age began to show, starting from the sixth and seventh rounds as Dawson became the aggressor.
The early rounds were marked by a bad cut Dawson suffered in the fourth over his left eye as a result of an accidental head butt from Hopkins.
The cut brought Dawson's corner into play as they battled successfully to stop the bleeding between each round.
Dawson said the head-butts were part of Hopkins' game plan.
"He is a dirty fighter that old man," Dawson said. "I knew the head-butts were coming.
"You could hear our heads clash together. The head-butts were blatant but I kept my composure."
An incident at the end of the fifth round recalled the odd finish to their fight in October.
As the bell sounded to end the round, Dawson grabbed Hopkins with both hands around the waist and swung him across the ring and almost through the ropes.
Hopkins returned the favour with one minute left in the 11th round by wrestling Dawson to the floor as the fight deteriorated and the clinches started to outnumber the punches.
Hopkins, who fell to 52-6-2 with 32 knockouts, was seeking to defend his title against Dawson six months after their first title clash was cut short in round two as Dawson lifted Hopkins by the leg and tried to throw him to the canvas.
The fight was halted with Hopkins saying he suffered a left shoulder dislocation. Referee Pat Russell awarded the fight to Dawson, saying no foul was committed, but the result was overturned to a no-decision and the rematch ordered.