Old Meets New As Gwen, Ciara, Simple Plan, Peas, J. Lo Rock Wango Tango

Stefani steals the show with a marching band and three costume changes in her 30-minute set.

ANAHEIM, California -- There was a palpable "back to the future" vibe at KIIS-FM's eighth annual Wango Tango festival this past weekend. For one thing, Saturday's show was the first time the event has returned to Angel Stadium since the first Wango Tango back in 1998, and 70,000 people were on hand to celebrate.

But the show also saw the old school meeting the new, as relative newcomers Natalie, Ciara, Simple Plan, Frankie J and Baby Bash bumped elbows with seasoned Tango veterans like the Backstreet Boys, Black Eyed Peas, Will Smith and Jennifer Lopez.

On at least one occasion, old and new literally bumped elbows. Backstage in the press room, Simple Plan broke into a rendition of Backstreet's "Quit Playin' Games (With My Heart)" only to discover the Boys were right next door: SP's Sebastien Lefebvre was shocked to peek through the curtain and see the boy band staring back. "Heeey!" was heard all around as the two bands crossed over into each other's interviews.

Later, Nick Carter, Brian Littrell, A.J. McLean, Howie Dorough and Kevin Richardson broke out into Simple Plan's "Addicted." "Oh my God, that's going to be the best moment for the next two months," laughed SP drummer Chuck Comeau. It seems that the two groups may already be sharing ideas, as both used stools during their sets: Simple Plan chose to sit during their low-key set, and the Boys used the stools for some old choreography with "The Call" and "I Want It That Way."

Introduced by emcee Ryan Seacrest, the Boys also showcased a couple of new songs from their forthcoming album, Never Gone, which drops on June 14. One of the songs, "I Still," was dedicated to all their old fans in the audience. "On behalf of the guys, we want to dedicate this song to every Backstreet fan that came out tonight," Brian Littrell told the crowd. "Everybody (Backstreet's Back)" closed out the set as the five connected hands and took a bow together.

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Click for photos from Wango Tango's eighth annual KIIS-FM festival

The group turned in an energetic set considering the day's 90-degree heat. Ryan Cabrera, who walked onto the stage in jeans and a fitted black blazer, ditched the jacket after his first tune, "Kinds of Sadness." "It's a little hot out here," he joked. "It's time to start taking some clothes off."

Kelly Clarkson used the weather to her advantage, rocking a cut-off Rolling Stones T-shirt that bared her belly (she also channeled Madonna by wearing a cut-off black glove). The first American Idol bounded across the stage during her set, getting the crowd pumped with "Since U Been Gone" and "Miss Independent" before slowing it down with an acoustic version of "Breakaway."

Jennifer Lopez, who was escorted to the stage with hubby Marc Anthony by her side, wore a shredded white shirt over a black tee that exclaimed "F--- It!" A surprise cameo by rapper Fat Joe brought the crowd to its feet as the duo performed Lopez's new single, "Hold You Down," and even a bit of Joe's "Lean Back."

A very svelte (and newly platinum blonde) Lindsay Lohan performed hits from her debut album, Speak, while Frankie J, Baby Bash and Natalie all took time off their current package tour to play short sets for the hyped-up crowd. Ciara peeled off "Goodies" and "1,2, Step" before being rushed off of the stage at the end of her performance for an undisclosed reason.

Hit-filled sets from the Black Eyed Peas and Ludacris got the crowd up on its feet, but clearly, the most anticipated artist of the night was Gwen Stefani, who pulled out all the stops for her first Tango appearance as a solo artist. With a full marching band in tow, Gwen rocked the crowd with "Hollaback Girl," "Rich Girl," "What You Waiting For?" and others as the Harajuku Girls pranced around the stage in yellow track uniforms. Ms. Stefani zipped through three costume changes during her 30-minute set, running around the stage in stilletos while her hubby, Gavin Rossdale, waited in the wings.

Still, the best-entrance honors for the night must be given to Big Willie himself -- Will Smith -- who was carried onto the stage in a makeshift throne, summoning memories of his title role in "Ali." Drumbeats resonated throughout Angel Stadium as an announcer repeatedly chanted "The champ is here!" Donning a black tee with the words "I am hip-hop" emblazoned across the front, Smith got the party started by introducing his special-guest DJ and childhood friend, DJ Jazzy Jeff. After a set filled with favorites like "Gettin' Jiggy Wit It," "Miami" and his new single, "Switch," Smith returned to his Fresh Prince roots as he and Jeff finished the set with their Grammy-winning hit "Summertime."

The Pussycat Dolls closed out the show with their single "Don't Cha," but were battling nerves early in the day. "We are so psyched [to play tonight]," lead singer Nicole Kea said. "We can't wait. It's going to be amazing." Like a lot of the day's performers, the Dolls were newcomers to the Wango stage, but ended the night like veterans.

For more sights and stories from concerts around the country, check out MTV News Tour Reports[/article].