Aside from headliners the Flaming Lips, it's hard to imagine a more crowd-pleasing set than the one the Thermals played at the 2009 Pitchfork Music Festival on Sunday. Interwoven with the riffy goodness of originals like 'Now We Can See' and 'A Pillar of Salt' were four covers of indie and alt-rock chestnuts.

Taking the stage at Chicago's Union Park with the bouncy enthusiasm of a punk rock Mickey Mouse Club -- drummer Westin Harris alone had enough ra-ra spirit for the entire festival -- the Portland trio immediately launched into Sonic Youth's '100%' (from 1992's 'Dirty'), and if it wasn't universally recognized, the band can feel good that the next number, their own 'Returning to the Fold,' definitely was.

"I give this set a 9.3 so far," frontman Hutch Harris said, and was then greatly disappointed no one seemed to like his Pitchfork joke (one that has surely been made before). "Internet thing," he mumbled. Songs by Nirvana ('Sappy") the Breeders (a majestic 'Saints') and Green Day ('Basket Case') would follow.

After the show, Harris and bassist Kathy Foster told Spinner they've been playing the Nirvana and Breeders songs fairly often, but the other two were new. "Those are all of our favorite songs," Foster said. "We were a little nervous, but it was really fun."

Harris said he wasn't sure how 'Basket Case' would pop. "Pitchfork's such a hipster thing," he teased. "You've got to play it a little cooler. And it's Chicago too, so you gotta be cool. But we're not embarrassed to love Green Day."

Nor was anyone in Union Park, it seemed, as the song was an unquestioned highlight of the day. "I loved that everybody started singing along right away," Foster said with a giggle. "People were like, 'Yeah!' It was awesome."