Billboard Music Awards 2015: 10 most memorable performances

The rock gods opened the show with a sizzling performance of their 1984 hit. It was the first televised awards show performance with the band’s current lineup (including Eddie Van Halen's son Wolfgang on bass) and they didn’t skimp on the fun, party-starting vibes. David Lee Roth gets bonus points for pairing a flashy suit with Under Armour gear.

Trainor continued her hot streak with a dramatic performance of her latest single. The 21-year-old diva hit her notes with pinpoint accuracy, and when Legend, ever the consummate gentleman, waded across the foggy stage to join her, he guaranteed the performance as one of the evening’s best.

Moody and melancholic, Hozier wailed his way through the song we've all heard a hundred (million?) times by now. Never has morbid somberness sounded oh-so-good on a television awards show.

The youngest of the three Jo Bros bandmates has proven himself as a solid solo artist since the group's 2013 demise. Still not convinced? Tonight's performance showed him in full-blown '80s pop star glory, shredding on his throwback Gibson Moderne guitar in front of a crazy penetrating laser show. Totally tubular!

Perched on crates on a stage shockingly devoid of pulsing lights, the kings of radioactive bombast scaled back for a tender tribute to the late singer Ben E. King, delivering a harmony-laden cover of “Stand By Me.” On paper, it could've been a failure; in practice, it was the rare awards show moment that transcended glitz and had genuine poignance.

No back-up dancers, no flashy light shows—just a couple of country pros with icon Hill singing LBT's (somewhat controversial) ode to friendship.

David Lee Roth called her out during Van Halen's performance and Sam Smith gave her booty its own shout out during his acceptance speech, but finally it was the "Anaconda" rapper's turn to do the talking. And she nailed it: her performance of "The Night Is Still Young" and "Hey Mama" was the most rave-tastic song of the night.

The Scottish group were introduced by Molly Ringwald for the song made famous in her Brat Pack classic The Breakfast Club. "It's still unforgettable!" the actress said of the tune, released 30 years ago. And she was right: Simple Minds delivered the night's most uplifting performance.

American Idol may be nearing the end, but its first season winner shows no signs of slowing down. Performing her new single, the pop star one-upped divas like Mariah Carey by, you know, actually hitting the high notes.

You could barely see him amid the flash of the pyro—and you could hardly hear him because he was bleeped like crazy. But damn if the rapper didn't deliver the night's craziest moment, with an insane, balls-to-the-wall show closer.