Former middleweight champion Kelly Pavlik has withdrawn from Saturday's 10-round fight against Darryl Cunningham for unknown reasons.

Pavlik was scheduled to fight at the Covelli Centre in his hometown, with the bout to be televised nationally on Showtime.

Pavlik's withdrawal was announced Tuesday by Top Rank, Pavlik's promoter. Todd duBoef, president of Top Rank, said he was "very disappointed at Kelly's sudden decision to discontinue the rebuilding of his boxing career."

In January, Pavlik checked out of the Betty Ford Center in Rancho Mirage, Calif., after two months of treatment for alcoholism.

Pavlik most recently fought in May, when he beat Alfonso Lopez by majority decision on the undercard for Manny Pacquiao-Shane Mosley.

Before then, he hadn't fought since April 17, 2010, when Argentina's Sergio Martinez took his two middleweight title belts in a bloody unanimous decision that ended Pavlik's 2½-year reign atop the division.