Anthony Dirrell regained the vacant WBC super-middleweight world title with a technical split decision over Turkey's Avni Yildirim in Minneapolis.
The fight was stopped in the 10th round because of a cut over Dirrell's eye, caused by an accidental head butt.
The contest went to the scorecards with two judges scoring it to the American and one giving it to Yildirim.
"I wanted to keep going and finish like a champion," said Dirrell, who admitted he did not know how bad the cut was.
The 34-year-old first won the title with a unanimous decision over Sakio Bika in August 2014, only to lose it in his first defence against Badou Jack.
The first title came after he was sidelined for almost two years when was diagnosed with non-Hodgkin lymphoma in 2006.
"This one is just as joyful," he added, after winning the title which was left vacant when American David Benavidez was stripped of the belt and suspended after testing positive for cocaine in August.
Dirrell expects 2019 to be his last year before he retires, but before he departs he's eager for a unification bout against International Boxing Federation title holder Caleb Plant.
A title fight against Benavidez, who is due to return to the ring in March, could also be on the cards.
The division also contains Liverpool's Callum Smith, the WBA world super-middleweight title holder, plus Chris Eubank Jr who beat James DeGale in London on Saturday.