Miley Cyrus and Taylor Swift Perform "Fifteen" at Grammy's

Now we know why Taylor Swift is selling out most of her concerts. It's because she's extremely talented! Taylor and her best bud Miley Cyrus performed one of Swift's songs titled, Fifteen.

Both of them did a great job. Taylor was so sympathetic while she was singing and Miley brought great edginess to the song.

Watch the performance below: