Chicago punk-poppers Fall Out Boy [ tickets ], currently headlining the Nintendo Fusion Tour [ tickets ], have everything it takes to capitalize on the buzz that's built up around them.

Stoking that buzz is a combination of good looks--courtesy of eye-liner-happy bassist/songwriter Pete Wentz--snappy songs, a beef with labelmates The Killers (whether or not it's in jest is in question), and a live show that's so aggressive it makes the Warped Tour look like Lilith Fair.

A mosh pit made up most of the standing-room-only crowd at the Mesa Amphitheatre in Mesa, AZ, on Wednesday (10/26). The enthusiastic (to use the term lightly) audience, fists pumping in the air, took every opportunity to sing the lyrics for singer/guitarist Patrick Stump.

Forgoing a mind-blowing encore--the band says it doesn't believe in encores--Fall Out Boy rolled out most of its tricks early in the show. Through the PAs, an announcer said "Welcome to the Greatest Show on Earth." As confetti blew into the venue, the band kicked off the show with a punked-out "Our Lawyer Made Us Change the Name of This Song So We Wouldn't Get Sued," the opening track from its breakthrough album, "From Under the Cork Tree."

Mid-set, Fall Out Boy introduced an urgent rendition of its hit "Sugar, We're Going Down," which increased the activity of the mosh pit tenfold. But the fans weren't the only aggressive ones. Bassist Wentz spun in circles, threw his bass in the air, jumped off a 6-foot high prop, and utilized the full stage with his instrument. Stump mostly remained stationed behind the mic, but occasionally hopped on a monitor to encourage the crowd to sing the band's lyrics. (At one point, Wentz said the band had its monitors turned up as high as possible, but the audience still overran them.)

"Every single show is better than the last one, so that means every single one of you has been to the best Fall Out Boy show," Wentz told the crowd.

Wentz's microphone went out as he spoke, a frequent problem during the show--especially during the shimmy-worthy song "Sophomore Slump or Comeback of the Year."

The group's set was split into two halves, with the first devoted to new material, and the latter portion devoted to diehard fans who bought the group's previous albums. There was a brief intermission between to the two sections.

"We've gone to shows and they just go ahead and play new s--- all the time," Wentz said. "We're dedicating the second half to old school fans,"

Wentz continually referred to the women in the crowd, but when the old school set kicked in, he acknowledged the members of his own gender. "This is for the boys club. I want to see a circle mosh pit," he said.

With Wentz's enthusiastic on-stage persona, he belonged in the pit along with the fans, all of whom sang along with older material. Based upon the response that Fall Out Boy received, it's clear that they have the staying power.