Green Day Trash Justin Bieber (And Guitars) At iHeartRadio Fest

Plus: Pink joins No Doubt for 'Just a Girl' during Las Vegas festival's first night.

Some of the biggest chart-toppers celebrated the end of summer in flashy fashion Friday when they gathered for the second annual iHeartRadio Music Festival, a megastar affair that included sets from Green Day, Lil Wayne and Usher.

With such an A-list lineup, it was expected that there would be a few surprises in store for the thousands of fans that packed Sin City's MGM Grand Theater. Among the evening highlights included an impromptu rant from Green Day lead singer Billie Joe Armstrong about the band's set getting cut short, which preceded by a classic rock-and-roll moment as the band began to trash their instruments onstage.

During the band's tune "Basket Case," Armstrong, clearly annoyed at the one-minute warning at the back of the arena, stopped mid-performance to vent his frustrations. "I'm going to play a f---ing new song," he said. "F--- this sh--. Gimme a f---ing break. One minute left. One minute f---ing left. You're going to give me one minute."

Justin Bieber (who wasn't even at the show) caught the wrath of the rocker's frustrations before the band walked offstage, with Armstrong saying, "I'm not f---ing Justin Bieber, you mother----ers. You've got to be f---ing joking. I got one minute. One minute left. Now I got nothing left."

Green Day's freakout wasn't the only eye-popping moment of the night. Pink joined No Doubt for a surprise duet of the band's hit "Just a Girl." It seemed like a regular rocking performance by the band until Gwen Stefani introduced the pop star about a minute in. Before sharing lines of the second verse, both pop stars kneeled to the concert floor to give each other a friendly kiss on the cheek.

Keyshia Cole was another surprise performer of the night as she shared the stage with Lil Wayne for a performance of the pair's collaboration "Enough of No Love."

Highlights will continue throughout the weekend as a second batch of performers (Taylor Swift, Pitbull and Linkin Park) will take the stage on Saturday evening (Saturday 22).