The pop crooner was in perfect form at the iHeartRadio music festival Saturday night at the MGM Grand Garden Arena. He wowed with his slick moves and energetic vibe.
Justin Timberlake was also a fan favorite. The pop star closed the five-hour plus concert, singing hits like "Mirror" and "SexyBack." Paul McCartney kicked off the show, playing a bunch of new songs from his upcoming album. And R&B singer Miguel and rapper Drake also earned cheers.
While men dominated Saturday, Ke$ha gave an impressive performance of her hits. She even brought out Joan Jett and the two sang "Bad Reputation." But Miley Cyrus was building on her bad reputation: She caused a stir when she entered the stage in a fishnet dress and tape covering her nipples.
Maroon 5, Tim McGraw and Phoenix also performed on the second night of the two-day festival.
GUYS NIGHT OUT (OR ONSTAGE)
Bruno Mars led the pack of men who entertained the crowd of thousands at the iHeartRadio festival. The singer was smooth as ever: He kicked off his set with fun, upbeat numbers "Locked Out of Heaven" and "Treasure," but transitioned to a soulful and passionate performance of "When I Was Your Man." He earned whistles from the audience.
Mars reached epic heights when he sang "Runaway Baby" - he was funky and even imitated James Brown's signature dance moves. The legend would be proud. The singer-songwriter-producer finished with a smoky, steamy rendition of his latest single, "Gorilla."
Justin Timberlake also held his own with the night's closing performance. Floyd Mayweather, who's dominating win over Canelo Alvarez last week in Las Vegas was the richest fight ever, introduced Timberlake as "the heavyweight champion of music." His set included "Cry Me a River," ''Take Back the Night" and "Like I Love You."
Drake got concertgoers out of their seats when he performed "HYFR" and "Started from the Bottom."
"I'm here to party," he told the crowd.
Miguel was in a similar mood: After performing "Adorn" and "#Beautiful," he urged the crowd to "have a good night and make some bad decisions."
There's no end to Miley Cyrus' antics.
The 20-year-old performed three songs at the iHeartRadio festival - all in a dress that revealed most of her body.
She sang her hits "We Can't Stop" and "Wrecking Ball," where her eyes were watery.
Britney Spears introduced the singer at the festival; the two worked on a song that will appear on Cyrus' new album, "Bangerz," out Oct. 8
"I'm sure everyone's going to be talking, which is what she wants," said Miguel, who added he "only caught a couple glimpses" of Cyrus' performance.
The singer-actress also performed a similar set at iHeartRadio's outdoor event earlier in the day.
A ROCKING SURPRISE
Joan Jett celebrated her 55th birthday in a big way: She joined Ke$ha onstage and earned roaring cheers from the crowd.
She was excited on the guitar in an all red ensemble as she and Ke$ha sang "Bad Reputation." Fireworks burst after the performance and Ke$ha yelled "happy birthday." She also got the crowd to say it to Jett as well.
"It's something a little different than we usually do, but it's exciting because the music is quite diverse," Jett said in an interview backstage about performing at the festival. "So it's going to be fun to play."
Joan Jett and the Blackhearts will release a new album, "Unvarnished," on Sept. 30.
"It's rock 'n' roll straight up," she said. "I'm very proud of the record. I think there's some great songwriting on it."
McCARTNEY PUSHES 'NEW' ALBUM
Paul McCartney had one thing in mind at the iHeartRadio: promote his new album.
The former Beatle will release "New" on Oct. 15. He mostly played new tracks for the crowd, including the album's title track and first single. The word 'new" descended from the ceiling before he sang the song.
"This is not a new song," McCartney said before singing "Another Day," which brought new life to the audience.
The 71-year-old switched from the guitar to the piano onstage, where he finished with the electrifying "Live and Let Die." The performance featured extremely loud fireworks, fire blazing and yellow and red lights beaming. The arena felt - and smelt - like the 4th of July.
BACKSTAGE CHRONICLES: THE KARDASHIANS
The cameras were rolling even though the Kardashians weren't filming their reality show.
Backstage at the iHeartRadio festival, a girl snapped a photo of Kourtney Kardashian when she wasn't camera ready, which annoyed the celebrity.
"That was a great shot of me pulling up my pants," the oldest of the ubiquitous family clan said.
Kourtney was joined by Khloe as well as Kylie and Kendall Jenner. The girls were dressed in all black, and Kourtney sported a shirt that read "like a virgin."
The sisters introduced Drake on Saturday night.