Old School Rules At IHeartRadio Music Festival

John was one of top performers Friday night at the MGM Garden Arena in Las Vegas. Katy Perry, Chris Brown and Robin Thicke and others also hit the stage.

But John was the crowd’s favorite – he earned a standing ovation after his third song.

Adam Lambert was equally as enduring when he performed with Queen. Pop-rock trio fun. also sang with iconic rock band.

Other performers during the five-hour concert included Keith Urban, Muse and J. Cole — acts who also impressed the crowd.

Justin Timberlake, Paul McCartney and Bruno Mars will close the 2-day iHeartRadio festival Saturday, but here’s a breakdown of day one:

HE STOLE THE NIGHT

From the moment Elton John went from playing the piano while sitting to sitting on top of the piano to singing, he captured the entire audience at the MGM Garden Arena.

The 66-year-old was fiery on his red piano, belting tunes like “Tiny Dancer” and “Bennie and the Jets.”

“Good evening, Vegas!” he yelled, sporting a dark glittery blazer.

John, who recently had surgery to remove his appendix, didn’t show any signs of slowing down during his five-song set. He was vocally loud and clear, and he even made a new song, “Home Again,” feel classic. (John will release a new album, The Diving Board, on Tuesday).

Fittingly, the icon closed with “I’m Still Standing.”

LAMBERT IS READY FOR THE THRONE

Adam Lambert is no Freddie Mercury, but he’s a scary good stand-in.

The “American Idol” alum electrified the crowd with his perfect high notes on songs like “We Are the Champions” and “Who Wants to Live Forever.” He had the right energy and sang a handful of songs with an ease that proved this is only the beginning for the 31-year-old.

Pop-rock trio fun. also sang with Queen, and lead singer Nate Ruess had hard shoes to fill following Lambert. But the singer held his own during “Somebody to Love.”

“Thank you to Queen for making this dream come true,” Ruess told the crowd.

Lambert came back onstage and the musicians closed the night with “We Are the Champions,” as fun.’s Jack Antonoff playfully strung the guitar next to Brian May.

NOT SO PITCH PERFECT

While Katy Perry had shining moments during her eight-song set at the iHeartRadio festival, she had pitchy moments, too.

The pop singer wasn’t in her best vocal form when singing “Wide Awake” and “California Gurls.” Perry was backed with dancers and she did some choreography herself, but dancing isn’t her strong suit.

The 28-year-old hit a better note with the crowd during “Teenage Dream,” and she had her best performance when she closed with “Roar.”

“Are you ready to roar?” she asked the crowd. “Me too.”

Chris Brown was in similar shape to Perry: He wasn’t vocally appealing – he relied heavily on autotune – and he didn’t dance as strong as he’s done in the past.

But like Perry, he closed the night the right way: Brown was full of Michael Jackson-esque moves during “Fine China.”

INTRODUCING J. COLE

J. Cole knew the crowd at the MGM Grand Arena wasn’t too familiar with him, but the rapper didn’t let that stop him.

“Because I’m well aware,” he said. “A lot of people in the building are like, ‘Who the (expletive) is this?’ and I’m cool with that.”

The protege of Jay Z, who was nominated for the best new artist Grammy last year, performed his well-known urban radio hits “Work Out” and “Can’t Get Enough,” where the rapper infused some of Jay Z’s “I Just Wanna Love U (Give It 2 Me).”

R&B singer Miguel joined J. Cole onstage for “Power Trip,” but it was TLC’s appearance on “Crooked Smile” that really ignited the audience.

ONE OFFS

Robin Thicke, who has the year’s longest running No. 1 song with “Blurred Lines,” opened the iHeartRadio festival singing the song to various women in the crowd. He worked his way to the stage, saying after his performance: “There are a lot if beautiful women here.”

Then he added: “You guys don’t look bad either.”

But Thicke wasn’t the only act to perform one song and leave. Ylvis, the Norwegian duo who have a viral hit with the song “The Fox,” also hit the stage Sunday. The brothers were in fox costumes, and while visually their performance felt like a gimmick, their voices were surprisingly appealing.