Even before Fall Out Boy traveled to Los Angeles to shoot their video for "This Ain't a Scene, It's an Arms Race," they were already touting it as the biggest and best thing they've ever done.

And while we can't vouch for the clip just yet -- it premieres Tuesday on "TRL" -- we're already sure of one thing: It's certainly the most dangerous thing they've ever made.

During the shoot, which took place at six locations in L.A. late last month, bassist Pete Wentz injured his back while, as he puts it, "doing a stunt." And while he wouldn't elaborate on just what that stunt entailed, he did fill in fans -- via pair of posts on Fall Out Boy's Web site -- on the pain he's been dealing with while FOB soldier on through various Christmas-themed radio events (see [article id="1547752"]"Fall Out Boy Feel Like Losers While Foo Fighters Win Big At Radio Fest"[/article]).

"I wanted to apologize to people who came out to the last couple warm-up shows -- I have done something to my back that makes it hurt for me to even walk," he wrote in one post on FallOutBoyRocks.com. He then added in another: "I did something to my back while doing a stunt for the video. I think it will all be worth it when the video comes out in the end. I hope it is something you're gonna love. No shows will be canceled, but like I said, I feel terrible when I don't feel like I am able to give absolutely everything I have on the stage. You know what they say, 'No pain, no gain,' and all."

Bob McLynn, a spokesperson for Fall Out Boy's management, confirmed that Wentz did hurt his back on the "Scene" video but wouldn't reveal just how he did it. McLynn did add that Wentz has been "playing in pain for about two weeks now and he needs to get another checkup.

"He hasn't been able to rest ... and that's the problem," McLynn continued. "He has swelling in the middle of his back, and he still needs to get it checked out, but he's committed to doing as many dates as possible. He was supposed to have it checked out in Los Angeles, but he had to go play KROQ's [Almost Acoustic Christmas], then fly out to Seattle, so he didn't get to have it looked at by a doctor. Even when the band has days off, like they did in Minneapolis the other day, they're still out doing things for the record."

McLynn says Fall Out Boy won't be forced to cancel any dates on their upcoming Friends or Enemies tour (see [article id="1547305"]"Leak Was True: Fall Out Boy Announce Friends Or Enemies Tour Dates"[/article]). He even went so far as to remind fans that tickets for the jaunt go on sale this Saturday.

"Like I said, he's committed," McLynn chuckled. "He'll be there, and so will Fall Out Boy."