Katie Peterson, left, and Jesse McCartney arrive at the Billboard Music Awards at the MGM Grand Garden Arena on Sunday, May 17, 2015, in Las Vegas. (Photo by Eric Jamison/Invision/AP Photo)

Kylie Jenner arrives at the Billboard Music Awards at the MGM Grand Garden Arena on Sunday, May 17, 2015, in Las Vegas. (Photo by Eric Jamison/Invision/AP Photo)

50 Cent, left, and Rita Ora present the award for top hot 100 song at the Billboard Music Awards at the MGM Grand Garden Arena on Sunday, May 17, 2015, in Las Vegas. (Photo by Chris Pizzello/Invision/AP Photo)

Charli XCX arrives at the Billboard Music Awards at the MGM Grand Garden Arena on Sunday, May 17, 2015, in Las Vegas. (Photo by Eric Jamison/Invision/AP Photo)

Kendall Jenner arrives at the Billboard Music Awards at the MGM Grand Garden Arena on Sunday, May 17, 2015, in Las Vegas. (Photo by Eric Jamison/Invision/AP Photo)

Giuliana Rancic arrives at the Billboard Music Awards at the MGM Grand Garden Arena on Sunday, May 17, 2015, in Las Vegas. (Photo by Eric Jamison/Invision/AP Photo)

Estelle arrives at the Billboard Music Awards at the MGM Grand Garden Arena on Sunday, May 17, 2015, in Las Vegas. (Photo by Eric Jamison/Invision/AP Photo)

Host Chrissy Teigen speaks at the Billboard Music Awards at the MGM Grand Garden Arena on Sunday, May 17, 2015, in Las Vegas. (Photo by Chris Pizzello/Invision/AP Photo)

Nicki Minaj performs at the Billboard Music Awards at the MGM Grand Garden Arena on Sunday, May 17, 2015, in Las Vegas. (Photo by Chris Pizzello/Invision/AP Photo)

Serayah arrives at the Billboard Music Awards at the MGM Grand Garden Arena on Sunday, May 17, 2015, in Las Vegas. (Photo by Eric Jamison/Invision/AP Photo)

Stefanie Scott arrives at the Billboard Music Awards at the MGM Grand Garden Arena on Sunday, May 17, 2015, in Las Vegas. (Photo by Eric Jamison/Invision/AP Photo)

Model Kendall Jenner (L), designer Olivier Rousteing and model Jourdan Dunn arrive at the 2015 Billboard Music Awards in Las Vegas, Nevada May 17, 2015. (Photo by L. E. Baskow/Reuters)

Designer Olivier Rousteing and model Jourdan Dunn arrive at the 2015 Billboard Music Awards in Las Vegas, Nevada May 17, 2015. (Photo by L. E. Baskow/Reuters)

Model Chrissy Teigen arrives at the 2015 Billboard Music Awards in Las Vegas, Nevada May 17, 2015. (Photo by L. E. Baskow/Reuters)

Singer Jennifer Lopez arrives at the 2015 Billboard Music Awards in Las Vegas, Nevada May 17, 2015. (Photo by L. E. Baskow/Reuters)

(L-R) Actress/singer Zendaya, actress Hailee Steinfeld, musician Taylor Swift, model Lily Aldridge and model Martha Hunt arrive at the 2015 Billboard Music Awards in Las Vegas, Nevada May 17, 2015. (Photo by L. E. Baskow/Reuters)

Singer Dencia arrives at the 2015 Billboard Music Awards in Las Vegas, Nevada May 17, 2015. (Photo by L. E. Baskow/Reuters)

Singer Dencia arrives at the 2015 Billboard Music Awards in Las Vegas, Nevada May 17, 2015. (Photo by L. E. Baskow/Reuters)

Hosts Chrissy Teigen and Ludacris speak at the 2015 Billboard Music Awards in Las Vegas, Nevada May 17, 2015. (Photo by Mario Anzuoni/Reuters)

Singer Rita Ora arrives at the 2015 Billboard Music Awards in Las Vegas, Nevada May 17, 2015. (Photo by L. E. Baskow/Reuters)

Singer Mariah Carey arrives at the 2015 Billboard Music Awards in Las Vegas, Nevada May 17, 2015. (Photo by L. E. Baskow/Reuters)

Singer Rita Ora arrives at the 2015 Billboard Music Awards in Las Vegas, Nevada May 17, 2015. (Photo by L. E. Baskow/Reuters)

Tracie Ellis Ross (L) and Laverne Cox announce the award for Top Billboard 200 Album won by Taylor Swift at the 2015 Billboard Music Awards in Las Vegas, Nevada May 17, 2015. (Photo by Mario Anzuoni/Reuters)

Iggy Azalea (L) accepts the award for top rap song for “Fancy” with Charlie XCX (R) at the 2015 Billboard Music Awards in Las Vegas, Nevada May 17, 2015. (Photo by Mario Anzuoni/Reuters)

Jennifer Lopez takes the stage at the 2015 Billboard Music Awards in Las Vegas, Nevada May 17, 2015. (Photo by Mario Anzuoni/Reuters)

Rapper 50 Cent and singer Rita Ora present the Top Hot 100 Song award during the 2015 Billboard Music Awards in Las Vegas, Nevada May 17, 2015. (Photo by Mario Anzuoni/Reuters)

Nicki Minaj performs “The Night is Still Young” at the 2015 Billboard Music Awards in Las Vegas, Nevada May 17, 2015. (Photo by Mario Anzuoni/Reuters)

Singer Taylor Swift poses backstage with her awards for Top Artist, Billboard Chart Achievement Award, Top Female Artist, Top Hot 100 Artist, Top Digital Songs Artist, Top Streaming Song (Video) for “Shake it Off” and Top Billboard 200 Album for “1989” at the 2015 Billboard Music Awards in Las Vegas, Nevada May 17, 2015. (Photo by L. E. Baskow/Reuters)

Singer Chris Brown performs “Fun” on stage at the 2015 Billboard Music Awards in Las Vegas, Nevada May 17, 2015. (Photo by Mario Anzuoni/Reuters)

Singer Taylor Swift poses backstage with her awards for Top Artist, Billboard Chart Achievement Award, Top Female Artist, Top Hot 100 Artist, Top Digital Songs Artist, Top Streaming Song (Video) for “Shake it Off” and Top Billboard 200 Album for “1989” during the 2015 Billboard Music Awards in Las Vegas, Nevada May 17, 2015. (Photo by L. E. Baskow/Reuters)

Taylor Swift arrives at the Billboard Music Awards at the MGM Grand Garden Arena on Sunday, May 17, 2015, in Las Vegas. (Photo by Eric Jamison/Invision/AP Photo)

Zendaya arrives at the Billboard Music Awards at the MGM Grand Garden Arena on Sunday, May 17, 2015, in Las Vegas. (Photo by Eric Jamison/Invision/AP Photo)

Lauren Jauregui, from left, Ally Brooke, Normani Hamilton, Dinah-Jane Hansen, and Camila Cabello of the musical group Fifth Harmony arrive at the Billboard Music Awards at the MGM Grand Garden Arena on Sunday, May 17, 2015, in Las Vegas. (Photo by Eric Jamison/Invision/AP Photo)

Celine Dion poses in the press room at the Billboard Music Awards at the MGM Grand Garden Arena on Sunday, May 17, 2015, in Las Vegas. (Photo by Eric Jamison/Invision/AP Photo)

Iggy Azalea, left, and Britney Spears arrive at the Billboard Music Awards at the MGM Grand Garden Arena on Sunday, May 17, 2015, in Las Vegas. (Photo by Eric Jamison/Invision/AP Photo)

Zendaya, from left, Hailee Steinfeld, Taylor Swift, Lily Aldridge, and Martha Hunt arrive at the Billboard Music Awards at the MGM Grand Garden Arena on Sunday, May 17, 2015, in Las Vegas. (Photo by Eric Jamison/Invision/AP Photo)