After [article id="1639926"]Christina Aguilera postponed a planned summer tour[/article] in support of her disappointing Bionic album, fans were probably wondering when they might see her onstage again. The singer, who recently announced her [article id="1650512"]divorce from husband Jordan Bratman[/article], finally got back in the live game on Saturday night, when she took part in Justin Timberlake and Friends, JT's benefit for the Shriners Hospitals for Children.

The show, held at Planet Hollywood's Theatre for the Performing Arts in Las Vegas, [article id="1646052"]was booked months ago[/article], before the personal turmoil in Aguilera's private life. But courtesy of a pointedly personal set list, it gave the singer a chance to remind the audience about her formidable performance chops.

According to E! Online, Aguilera, 29, came out in fighting shape, wearing a skintight black bodysuit with a leather bustier and ripping through a set of classics including "Ain't No Other Man," "Fighter" and "Beautiful."

JT was equally enthused about inviting his old touring pal and "Mickey Mouse Club" cohort back to the stage after several years away, introducing Xtina as "no contest, the best vocalist of my generation."

There was plenty of competition on the bill, as the show featured performances from Elton John, Lady Antebellum, Salt-N-Pepa, Diddy, Selena Gomez and T-Pain as well. Las Vegas Weekly reported that JT kept busy as master of ceremonies, sitting in for a set from Free Sol, who are signed to his label, rapping a bit with DJ Freestyle Steve, introducing the acts and strapping on an acoustic guitar for a breathtaking mini-set during the four-hour event.

That set included powerhouse performances, including a soulful solo acoustic version of "Cry Me a River," which blended into Bill Withers' "Ain't No Sunshine." Keeping the vibe mellow and intimate, he stayed seated on a stool with just his guitar and picked his way through "What Goes Around ... / ... Comes Around" with plenty of help from the audience before busting into a full-band version of "Rock Your Body."

E! reported that the newly single Aguilera made the most of her night, donning a Herve Leger dress and taking her crew of dancers out to the Tao club, where she waved to the crowd from her skybox. DJ Vice gave her a shout-out, calling Xtina "the sexiest lady in the world" as the crowd snapped photos.

The Timberlake show was a good warm-up for another live gig Aguilera has coming up, a November 21 [article id="1650546"]appearance at the American Music Awards[/article], where she will join a roster that includes Pink, Usher and Bon Jovi.