Sum 41's Whibley defies doctors to perform

Sum 41 frontman Deryck Whibley, who was injured last week in a bar fight while on tour in Japan, ignored doctor's orders and performed over the weekend.

The singer of the Ajax, Ont. pop-punk band was attacked by three people on Thursday and hospitalizedfor a slipped disc.

The band, whose hits include Fat Lip, In Too Deep and Still Waiting, played a show in Osaka on Saturday and another in Tokyo on Sunday as part of the Summersonic festival.

The group posted a note about the incident on their Twitter account around midnight ET on Friday, saying "Japanese police are looking into the matter."

An update on their website said Whibley would perform "despite doctor's instructions."

On Sunday,a fan's response on the band's Twitter account, from edamame41, said: "Thank you for the great show at #summersonic! I had a wonderful time!!"

According to the band's website, future dates on their Warped tour are still on. Their next concert will be Aug. 11 in Pomona, Calif.

Whibley married pop star Avril Lavigne in 2006. The couple separated last year.