UPDATE 9:21 p.m.
After an MRI scan, doctors have told Sum 41 frontman Deryck Whibley that he has a slipped disc in his back. He's been instructed to rest, but the band will still perform tomorrow at Japan's Summersonic Festival.
 

ORIGINAL POST: 8:13 a.m.
According to their Twitter, Sum 41's Deryck Whibley was attacked by 3 people at a bar in Japan last night and is currently in the hospital. Authorities are looking into the matter, however no further updates have surfaced. We will bring you more details on this story as it develops.