Kesha, Madonna & Miley Cyrus at the 2013 Billboard Music Awards at the MGM Grand Garden Arena on May 19, 2013 in Las Vegas, Nevada.

Miley Cyrus in Balmain and Givenchy shoes arrives at the 2013 Billboard Music Awards at the MGM Grand Garden Arena on May 19, 2013 in Las Vegas, Nevada. (Getty)

Taylor Swift in Zuhair Murad arrives at the 2013 Billboard Music Awards at the MGM Grand Garden Arena on May 19, 2013 in Las Vegas, Nevada.(Getty)

Emmy Rossum in Zuhair Murad arrives at the 2013 Billboard Music Awards at the MGM Grand Garden Arena on May 19, 2013 in Las Vegas, Nevada.(Getty)

Selena Gomez, in Versace, arrives at the 2013 Billboard Music Awards at the MGM Grand Garden Arena on May 19, 2013 in Las Vegas, Nevada.(Getty)

Jennifer Lopez in Zuhair Murad arrives at the 2013 Billboard Music Awards at the MGM Grand Garden Arena on May 19, 2013 in Las Vegas, Nevada.(Getty)

Ke$ha, in Givenchy, arrives at the 2013 Billboard Music Awards at the MGM Grand Garden Arena on May 19, 2013 in Las Vegas, Nevada.(Getty)

Hayden Panettiere, in a Halston Heritage dress, Giuseppe Zanotti shoes, a Jimmy Choo bag, and David Yurman jewelry, arrives at the 2013 Billboard Music Awards at the MGM Grand Garden Arena on May 19, 2013 in Las Vegas, Nevada.(Getty)

Kelly Rowland, in a Rami Al Ali gown, arrives at the 2013 Billboard Music Awards at the MGM Grand Garden Arena on May 19, 2013 in Las Vegas, Nevada.(Getty)

Jennifer Morrison, in a Kristian Aadvenik dress, arrives at the 2013 Billboard Music Awards at the MGM Grand Garden Arena on May 19, 2013 in Las Vegas, Nevada.(Getty)

Alyssa Milano arrives at the 2013 Billboard Music Awards at the MGM Grand Garden Arena on May 19, 2013 in Las Vegas, Nevada.(Getty)

Shania Twain arrives at the 2013 Billboard Music Awards at the MGM Grand Garden Arena on May 19, 2013 in Las Vegas, Nevada. (Getty)

Carly Rae Jepsen, in a Dyanthe dress, Isharya jewels, Gio Diev heels, and a Nancy Gonzalez bag, arrives at the 2013 Billboard Music Awards at the MGM Grand Garden Arena on May 19, 2013 in Las Vegas, Nevada.(Getty)

Chad Kroeger & Avril Lavigne arrives on the red carpet at the 2013 Billboard Music Awards at the MGM Grand in Las Vegas, Nevada, May 19, 2013. (Getty)

Audrina Patridge arrives at the 2013 Billboard Music Awards at the MGM Grand Garden Arena on May 19, 2013 in Las Vegas, Nevada.(Getty)

Kimberly Perry of The Band Perry arrives at the 2013 Billboard Music Awards at the MGM Grand Garden Arena on May 19, 2013 in Las Vegas, Nevada. (Getty)

Jenny McCarthy arrives at the 2013 Billboard Music Awards at the MGM Grand Garden Arena on May 19, 2013 in Las Vegas, Nevada.(Getty)

Nicki Minaj arrives at the 2013 Billboard Music Awards at the MGM Grand Garden Arena on May 19, 2013 in Las Vegas, Nevada.(Getty)

Amber Rose, in Gucci, arrives at the 2013 Billboard Music Awards at the MGM Grand Garden Arena on May 19, 2013 in Las Vegas, Nevada.(Getty)

Adriana Grande arrives at the 2013 Billboard Music Awards at the MGM Grand Garden Arena on May 19, 2013 in Las Vegas, Nevada.(Getty)

Nayer arrives at the 2013 Billboard Music Awards at the MGM Grand Garden Arena on May 19, 2013 in Las Vegas, Nevada(Getty)

Selena Gomez arrives at the 2013 Billboard Music Awards at the MGM Grand Garden Arena on May 19, 2013 in Las Vegas, Nevada.

Miley Cyrus arrives at the 2013 Billboard Music Awards at the MGM Grand Garden Arena on May 19, 2013 in Las Vegas, Nevada.

Taylor Swift arrives at the 2013 Billboard Music Awards at the MGM Grand Garden Arena on May 19, 2013 in Las Vegas, Nevada.

Jennifer Lopez arrives at the 2013 Billboard Music Awards at the MGM Grand Garden Arena on May 19, 2013 in Las Vegas, Nevada.

Nicki Minaj arrives at the 2013 Billboard Music Awards at the MGM Grand Garden Arena on May 19, 2013 in Las Vegas, Nevada.

Emmy Rossum arrives at the 2013 Billboard Music Awards at the MGM Grand Garden Arena on May 19, 2013 in Las Vegas, Nevada.

Amber Rose arrives at the 2013 Billboard Music Awards at the MGM Grand Garden Arena on May 19, 2013 in Las Vegas, Nevada.

Carly Rae Jepsen arrives at the 2013 Billboard Music Awards at the MGM Grand Garden Arena on May 19, 2013 in Las Vegas, Nevada.

Kesha arrives at the 2013 Billboard Music Awards at the MGM Grand Garden Arena on May 19, 2013 in Las Vegas, Nevada.

Stana Katic arrives at the 2013 Billboard Music Awards at the MGM Grand Garden Arena on May 19, 2013 in Las Vegas, Nevada.

Hayden Panettiere arrives at the 2013 Billboard Music Awards at the MGM Grand Garden Arena on May 19, 2013 in Las Vegas, Nevada.

Chloe Grace Moretz arrives at the 2013 Billboard Music Awards at the MGM Grand Garden Arena on May 19, 2013 in Las Vegas, Nevada.

Alyssa Milano arrives at the 2013 Billboard Music Awards at the MGM Grand Garden Arena on May 19, 2013 in Las Vegas, Nevada.

Ariana Grande arrives at the 2013 Billboard Music Awards at the MGM Grand Garden Arena on May 19, 2013 in Las Vegas, Nevada.

Madonna at the 2013 Billboard Music Awards at the MGM Grand Garden Arena on May 19, 2013 in Las Vegas, Nevada.

Shania Twain arrives at the 2013 Billboard Music Awards at the MGM Grand Garden Arena on May 19, 2013 in Las Vegas, Nevada.

Kelly Rowland arrives at the 2013 Billboard Music Awards at the MGM Grand Garden Arena on May 19, 2013 in Las Vegas, Nevada.

Jenny McCarthy arrives at the 2013 Billboard Music Awards at the MGM Grand Garden Arena on May 19, 2013 in Las Vegas, Nevada.

Jennifer Morrison arrives at the 2013 Billboard Music Awards at the MGM Grand Garden Arena on May 19, 2013 in Las Vegas, Nevada.

Nayer arrives at the 2013 Billboard Music Awards at the MGM Grand Garden Arena on May 19, 2013 in Las Vegas, Nevada.

Audrina Patridge arrives at the 2013 Billboard Music Awards at the MGM Grand Garden Arena on May 19, 2013 in Las Vegas, Nevada.

Kimberly Perry arrives at the 2013 Billboard Music Awards at the MGM Grand Garden Arena on May 19, 2013 in Las Vegas, Nevada.