Matthew Macklin enjoyed a winning start to life with new trainer Jamie Moore, clinching a unanimous points win over the previously unbeaten Lamar Russ.
Returning to action for the first time since losing in three to Gennady Golovkin, Macklin was always in control against an opponent who was a late replacement for the injured Willie Nelson.
The bout at Boardwalk Hall ended up going the distance, with the Birmingham-born middleweight awarded it by margins of 98-92, 97-93 and 96-94.
He will now hope to work his way into another shot for a major belt after beating Russ, who had never been beyond eight rounds before in his career.
The win is only the second for Macklin since the end of 2010. He stopped Joachim Alcine inside a round last year having previously failed in title challenges against Sergio Martinez and Felix Sturm.
It was his first outing with former foe Moore in his corner, the pair having fought seven years ago in a brutal British title fight that saw Macklin stopped by his rival in the 10th round.
Also in Atlantic City, Guillermo Rigondeaux retained his WBA and WBO super-bantamweight titles with a unanimous points victory of his own.
The Miami-based Cuban recorded a shut-out success over two-time bantamweight champion Joseph Agbeko, all three judges scoring the bout 120-108.
Rigondeaux, a two-time Olympic gold medallist who upset Nonito Donaire last April, dominated throughout without ever looking like stopping an opponent who was fighting at the 122lb-limit for the first time in his career.
"I came to do what I need to do," he said through an interpreter afterwards. "Every time out there, I try to improve. I'm improving every day. I had no problems in any round."
In the co-feature on Saturday night, middleweight James Kirkland registered a sixth-round TKO over previously unbeaten prospect Glen Tapia.