Nerd fight!

With tongues firmly planted in their respective cheeks, the Decemberists and Stephen Colbert are engaged in a diss fest over each other's green-screen antics.

The sardonic tiff started this week when Colbert introduced a new segment on his nightly Comedy Central show, The Colbert Report. In the segment, dubbed "Who's Riding My Coat Tails Now?," Colbert chastised Jeopardy and its host Alex Trebek for basing a question on Colbert's use of the name "Filliam H. Muffman" to describe the union of actors William H. Macy and Felicity Huffman.

He then turned his ire to the Portland, Oregon-based lit-rockers, who are participating in a mtvU contest that lets viewers reanimate them for the video new single "O Valencia!," for which they performed with their instruments in front of a green screen. Colbert accused the band of copying his "Green Screen Challenge" segment, in which he invited viewers to animate a background for his onscreen light saber antics.

He then encouraged viewers to enter the mtvU contest and reanimate Colbert himself into the video as part of the "Second Green Screen Challenge."

"See how well the [band] perform their trademark brand of hyperliterate prog rock when I'm slicing their leg off at the knee," he proclaimed before whipping out his light saber.

In an e-mail to Pitchfork, the Decemberists responded today, claiming to have beaten Colbert to the light saber gag.

"Mr. Colbert, assuming that we watch his show [ok, we do], went on to suggest that we had stolen his idea, calling us 'a bunch of coat tail riding jerks!' Who's riding on whose coat tails, sir?" the band wrote. "We already played out the light saber thing months earlier, live and on stage--sans animation, stunt double and fancy green screen--with pure rock, sweat and C batteries."

"We are asking our fans to help us win this epic battle," the band wrote. "That's right, we want you to help us defeat Stephen Colbert in our video! Show us how you would 'Mulch' him, take him down to the banks of the Ohio, put a cap in his Dockers. Send them to us here."

The winner of the contest lands a new iMac Intel Core 2 Duo and gets his or her animation premiered on mtvU and mtvU.com.

The band also issued a "Decemberists vs. Stephen Colbert Guitar Solo Challenge," inviting Colbert to "put down the pen and pick up the axe! Let's see what kind of a man you really are--let's SHRED. Let truth and good music prevail!!!"