Hard-hitting heavyweight Efe Ajagba (11-0, 9 KOs) has pulled out of his bout against Jack Mulowayi with a back injury suffered during training.
The bout was scheduled to be the opener of the Showtime telecast from Reading, Pennsylvania, on Saturday.
Sources tell ESPN that the replacement bout will feature another undefeated heavyweight, Frank Sanchez (13-0, 11 KOs), against Mulowayi.
Ajagba's trainer, Ronnie Shields, said the boxer suffered the injury while he was going through strength and conditioning drills.
"He strained his back last week," said Shields, who trains the Nigerian-born fighter in Houston. "He tried to continue on, but he couldn't even throw a punch. His back just got messed up.
"When he got home he said he laid down and he tried to get up, he couldn't get out of the bed. So he immediately went to the gym, they iced him down real good, put heat on him.
"It loosened up a little bit, he started training, started sparring and threw a punch and he was in pain. He just went down and said, 'I can't do anything.'"
Ajagba, 25, gained notoriety last year when Curtis Harper abruptly left the ring as the bell rang to begin their fight in Minneapolis, making Ajagba the winner by disqualification at one second of the first round.
Ajagba's last appearance was on July 20, where he scored a 10-round decision over Ali Demirezen in Las Vegas.
Moving forward, the hope is to get the 2016 Olympian another fight by the end of 2019, Shields said.