Audley Harrison knocked out journeyman Andrew Greeley in the third round as he had his first fight since April.
Harrison still believes he can become a world champion
The Briton, returning to the ring after two successive defeats, secured his win two minutes and 32 seconds into the third round of the Atlantic City fight.
Harrison's new trainer Buddy McGirt believes the 34-year-old is still capable of being a champion.
"Audley can be heavyweight champion," McGirt said. "I wouldn't be wasting my time if he didn't have it in him."
McGirt also trains Antonio Tarver, who lost to Bernard Hopkins on Saturday, and Arturo Gatti and is highly respected.
The American is confident he has the key to turning round Harrison's career, which went into freefall after losses to Danny Williams and Dominic Guinn.
"He's got all the tools, his problems are mental," said McGirt. "I can help him with that."
Greeley had won just 11 of his previous 23 heavyweight fights.
The bout featured on the undercard of Brian Minto's 10-round points decision win over Danny Batchelder.