Avril Lavigne's Ex Cancels Tour After Being Attacked

Credit: Denise Truscello/WireImage.com

Sum 41 have canceled their Vans Warped tour while their lead singer, Deryck Whibley, recovers from an attack at  a Japanese bar last week.

Said the group in a statement Wednesday, "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."

Whibley, 30, who split from Avril Lavigne in September 2009 after three years of marriage, was assaulted by three men after playing the Summer Sonic rock festival in Japan last week, according to reports.

PHOTOS: See Deryck and Avril's wedding pic -- and others!

The injury aggravated a prior disc injury from 2007. "He is expected to make a full recovery with the necessary treatment and rest," the band continued in a statement. See the top 10 rock 'n' roll front men.

They hope to pick up their European tour at the end of August.