Deryck Whibley, Avril Lavigne's ex hubby, won't be hitting the stage anytime soon due to a back injury he sustained after being attacked in a Japanese bar.

Sum 41 has decided to pull out of the Vans Warped tour while their 30-year-old lead singer recovers.

The following statement was released on the band's website:

"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. He is expected to make a full recovery with the necessary treatment and rest."

Whibley was attacked by three men in a bar after performing at the Summer Sonic rock festival in Japan. Sum 41 hopes to resume their European tour by the end of this month.

Lavigne, who's currently dating Brody Jenner, split from Whibley back in September 2009.

Deryck Whibley, Avril Lavigne's ex and frontman for Sum 41, is recovering in a Japenese hospital after being attacked at a bar.

The band is slated to play in Los Angeles next Wednesday, but first they were wrapping up their tour dates in Japan. Their next stop was scheduled for this weekend at the Summer Sonic Festival in Osaka, Japan.

On their Twitter page, Sum 41 released the following info:

In a recent update posted on their website, the band says, "It is unfortunate to say, but Deryck Whibley is still in the hospital ... We are waiting for results and we are hoping for the best. Thanks for your support."

No word on whether Sum 41's Summer Sonic Festival appearance will be cancelled.

Good thing Deryck Whibley didn't stop over at El Compadre! That could've been an awkward run-in with Avril and Brody...

Instead, the Sum 41 singer went out clubbing at Las Palmas with two hot babes, one of them being his girlfriend Hanna Beth Merjos. Guess him and Avril are def not getting back together! Think Deryck traded up or down?

Ex-spouses Avril Lavigne and Deryck Whibley both found themselves at Trousdale last night after Avril performed at the Race To Erase MS event in Century City.

Compounding the awkwardness was the fact that both Avril and Deryck showed up with new loves -- Avril was with boyfriend Brody Jenner and Deryck had a new girl on his arm!

Add to that the fact that Paris Hilton (who dated Deryck before he married Avril) was also at the club and you've got a love quintuple!

Other celebs who were at Hollywood's hottest spot last night were Katy Perry and Russell Brand, Hilary Duff, Nicky Hilton, Apolo Anton Ohno and Sophie Turner (gallery below.)

Hopefully he won't run into his estranged wife Avril one of these nights ... I mean, how incredibly awkward would that be?! Then again, that's a set of pictures we'd love to see!

Last night a solo Deryck Whibley was spotted at Voyeur in Hollywood, and the Sum 41 singer seemed to be enjoying his night of freedom. Soo ... when's he going to step out with another lady love?

While his ex-wife is off house-hunting with Brandon Davis, Deryck Whibley arrived solo to Madeo, where he often had romantic dinners with Avril in better times.

But before you break out the violins, Deryck was seen smooching a hot model last week, so we don't think he spent the night crying in his soup.

It’s been pretty obvious to everyone for months that these two were on the outs – but now Us reports Avril kicked her estranged hubby out of the 9.5 million dollar house they shared!

“She dumped him and told him she was leaving him. She wants to move on," a source told the mag. “Divorce papers will be filed any day now."

Kicking your man out on the street is kinda harsh - did Deryck do something to deserve that kind of treatment? Or is Avril just a cold-hearted snake?

Why should Avril have all the fun?

We spotted the soon-to-be ex Mr. Lavigne (if all the rumors are true, anyhow) leaving BOA with a pal last night. But it looks like he took a little doggy bag - or doggy cup - with him!

We have no idea what's in the red party cup...but at least he's not driving!