Sergey Kovalev has called for a third fight with Andre Ward after suffering a second controversial defeat to his American rival in Las Vegas on Saturday.
The Russian lost their first fight on points in November to relinquish the WBO, WBA and IBF light heavyweight titles to Ward, despite several pundits believing Kovalev was the winner.
Kovalev was unable to gain revenge as he was stopped in round eight, although he claimed that Ward was guilty of administering several low blows.
The 34-year-old also questioned the referee's decision to end the fight when he did, insisting he was still in a position to recover.
"I couldn't believe it," Kovalev told HBO in the ring. "Right now, I could have continued. I didn't feel that hurt. I could [still] win.
"Only a low blow [hurt me]. A low blow - and I felt this. Again, another one. The first one was on the border, and the second one a low blow.
"Why stop the fight? It's crazy. I want to get again a fight with him."
Meanwhile, Ward suggested he could move to a different weight level after extending his unbeaten record to 32 bouts.
"Maybe cruiserweight, I don't know," he said when asked about his plans.
"Cruiserweight, heavyweight, that's always been a dream of mine. I dream big and anything is possible."