From Britney Spears' Opening to Madonna's Prince Tribute, the Best Billboard Music Awards Moments

The Billboard Music Awards took place Sunday in Las Vegas.

Britney Spears kicked off Sunday night's Billboard Music Awards in Las Vegas on a high note with a super sexy performance that set the bar high for the rest of the night.

The pop princess, who took home the Millennium Award, sang a medley of her greatest hits, including "Womanizer" and "Toxic."

View: The Best Celebrity Baby Pictures

Following her performance, the 34-year-old singer posted on Instagram: “After tonight...All I Really Want is a Cheeseburger.”

The show was co-hosted by Ludacris and Ciara, who wore seven outfits, including a provocative silver dress on the red carpet.

Gwen Stefani and Blake Shelton put their romance on display as they belted out their new duet, “Go Ahead and Break my Heart.”

Kesha showed off her fighting spirit in matador-inspired duds. But onstage she avoided any reference to her ongoing legal battle with music producer Dr. Luke.

She performed a subtle cover of Bob Dylan’s “It Ain’t Me Babe,” with musician Ben Folds.

The crowd showed their support with a standing ovation.

Following her performance, she wrote a heartfelt note to fans on Instagram: "I'm so grateful for tonight and for the @billboardmusicawards_ for allowing me to sing. it's my form of prayer. it my therapy. it literally reaches the untouched corners of my soul. thank you for having me. I have so much gratitude." 

Madonna and Stevie Wonder’s highly-anticipated tribute to Prince has gotten extremely mixed reviews.

“Let me be the first to say... She sounds awful,” one viewer tweeted.

The performance also inspired many nasty memes with images of Prince looking unimpressed.

Prince's close friend and Today show anchor Tamron Hall said on Monday: “I didn't like it.”

Read: Prince Had Been Dead for Hours When He Was Found in His Home's Elevator: Report

But the performance has also been defended by another of Prince’s friends, Roots drummer and band leader Questlove.

He went on a lengthy Twitter rant to express his feelings about the tribute.

Watch: Dr. Conrad Murray Thinks Prince's Doctor Needs A Good Attorney