Pictures Of Rihanna, Gwen Stefani, Usher And More At The IHeartRadio Music Festival

The iHeartRadio Music Festival kicked off in Las Vegas on Friday with some of music's hottest names in town to perform. Ryan Seacrest emceed the event and was joined on stage at the top of the show by Britney Spears. The crowd went wild for Spears, who stepped out in a tight black mini dress and colourful pink and blue highlights in her hair. No Doubt was the first act to belt out their hits, with a mix of current singles like "Settle Down" and former chart toppers "Don't Speak," "It's My Life," and "Hellagood." The audience got a special surprise when Pink joined Gwen Stefani on stage for "Just a Girl." Miley Cyrus made the trip to Sin City as a presenter and teamed up with US Olympic gold medallist Ryan Lochte to introduce Lil Wayne to the sold out crowd. The night was a celebration of music genres with country, rap, R&B, pop, electric, and rock coming together to perform. Usher teamed up for a duet with Swedish House Mafia and had the crowd on their feet, though it was probably internet sensation Psy that got the most attention for his hot "Gangnam Style" dance moves. Rihanna closed down the four-hour block of live acts with her own high energy performance that included tracks from "Don't Stop The Music" to her latest release "Cockiness (Persuasion)." Check out all the pics here!