Lady Gaga, Coldplay, Bruno Mars, Carrie Underwood, Sting tapped for iHeartRadio Music Festival

Billed as "the biggest live music event in radio history," the two-day festival, set for the MGM Grand in Las Vegas in September, also features Alicia Keys, Nicki Minaj and Kelly Clarkson.

Though summer has already had its fair share of big-ticket, multiday festivals, Clear Channel is kicking off fall with what it's billing as "the biggest live music event in radio history."

The radio conglomerate on Monday announced the lineup for the inaugural iHeartRadio Music Festival, and the roster for the two-day festival, set for Sept. 23 and 24 at the MGM Grand in Las Vegas, is quite the who’s who among Top 40.

Night 1 features performances by Coldplay, Alicia Keys, the Black Eyed Peas, John Mayer, Carrie Underwood, Bruno Mars and Jane's Addiction. While Night 2 has Lady Gaga, Jennifer Lopez, Steven Tyler, Kenny Chesney, Nicki Minaj, Rascal Flatts, Kelly Clarkson, David Guetta, Sublime with Rome and special guest performances by Sting and Usher.

“This is a once-in-a-generation gathering of artists and fans from all over the country for a true, must-see music event,” Ryan Seacrest said in a video statement. “The iHeartRadio Music Festival, like the iHeartRadio digital radio service, will showcase top artists across all genres of music. Listeners from all over America will travel to Las Vegas to celebrate the next generation of iHeartRadio, while seeing the greatest musicians in the world on one stage.”

Seacrest will host the two-day affair, and each of the performances will stream live online, on mobile devices and through select radio station websites. More performers are expected to be added to the bill.

The festival supports the launch of the iHeartRadio app, which allows users streaming access to radio programming.

Pre-sale tickets are available now through Facebook; tickets go on sale to the general public through Ticketmaster on Saturday at 10 a.m. More info can be found on the festival's website.

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-- Gerrick D. Kennedy
twitter.com/GerrickKennedy

Photos: (Left) Lead singer of Coldplay Chris Martin performs during the Bilbao BBK Life music festival  on July 7 in Bilbao, Spain. Credit: Rafa Rivas/AFP/Getty Images; (Middle) Lady Gaga performs May 27 in New York City's Central Park for ABC's "Good Morning America." Credit: Evan Agostini/Associated Press; (Right) Bruno Mars performs at Radio 1's Big Weekend 2011 on May 15 in Carlisle, England. Credit: Dave J. Hogan/Getty Images