Fall Out Boy perform at Vice Bar on March 15, 2013 during the SXSW Music Conference.
Shannon Stewart for Fuse

During a sweaty, body-to-body set at Austin's Vice Bar on Friday night, the recently reunited Fall Out Boy turned in a ridiculously energetic performance for SXSW. Even though Patrick Stump claimed the one-in-the-morning start time was "a little past my bedtime" (hey, he is married now) and Pete Wentz wasn't too crazy that the cramped venue put zero space between the crowd and the band, none of that seemed to stop FOB from rocking at breakneck speed.

Jumping from one fan favorite to another, the Illinois outfit played most of their signature tracks with the kind of vigor that often comes to a band after taking a hiatus (check out our photographic proof if you don't believe us). After a little vacation from their material, FOB seem especially thrilled to be playing their hits again.

But the real star of the night was the crowd. Rabid FOB fans sang backup to every lyric on every song (yep, even the new single which has only been out a month) and brought the already steamy bar to a fever pitch.

It was a telling moment that when the band broke out their "Beat It" cover, the crowd offered their most muted response of the night. Which is crazy: This is a band with enough standout material that the least sizzling part of their hour-long set was a Michael Jackson cover. That means two things: FOB fans are seriously devoted and this band is putting together a catalog of songs that might last a lot longer than some naysayers think.