Avril Lavigne's Ex, Deryck Whibley, Recovers from Attack

Deryck Whibley Sum 41 has decided to pull out of the Vans Warped Tour while Deryck Whibley recovers from injuries sustained after being attacked in Japan. "Knowing that they are unable to deliver their signature high energy show, Sum 41 made the tough decision that a break is needed while Deryck begins rehabilitation for the slipped disc," the group said in a statement Wednesday.

Three men attacked Whibley in a bar in Japan, where the band was playing the Summer Sonic rock festival, E! Online reported. Last Friday, the band posted an update, saying, "After an MRI scan, it appears Deryck has slipped a disc in his back once again. Despite doctor's instructions, he has decided to play today's show at Summer Sonic regardless."The incident aggravated a previous disc injury from 2007.

"[We] are very disappointed that we have to pull off the tour. [But] we know that it would be more frustrating for the fans if we can't give it our all," drummer Steve Jocz said. "Deryck is doing everything he can to get himself better and we're there for him."

Sum 41 was also forced to cancel three Warped Tour appearances last week after Whibley came down with a severe case of bronchitis that threatened to damage his voice.

Whibley married fellow singer Avril Lavigne in 2006. The couple announced on September 17, 2009, that they had separated. Lavigne initiated divorce proceedings in October 2009, claiming "irreconcilable differences."