LOS ANGELES (AP) – WBC heavyweight champion Vitali Klitschko underwent back surgery that will prevent him from fighting until at least September.

Bernd Boente, Klitschko’s personal manager, said Wednesday that the 35-minute operation was performed a day earlier by Dr. Hyun Bae at an undisclosed hospital in the Los Angeles area. Boente said in a statement that a small spur was removed from Klitschko’s spine.

Plans called for Klitschko to defend his championship against Hasim Rahman this summer, but that will have to wait.

Klitschko hasn’t fought since last Dec. 12, when he stopped Danny Williams in the eighth round in Las Vegas. The 33-year-old champion has a 35-2 record with 34 knockouts. He will have to rehab for about six weeks before beginning to train, Boente said.

Klitschko won’t be allowed to fly for three weeks, preventing him from being in the corner when his younger brother, former WBO champion Wladimir, faces unbeaten Eliseo Castillo on Saturday in Germany. It will be the first time one of the brothers has not worked the other’s fight.

AP-ES-04-20-05 1754EDT