Taylor Swift joined the Rolling Stones onstage at Chicago's United Center June 3 to perform 'As Tears Go By' -- and of course, dance a bit with Mick Jagger.

The Stones legend introduced the song as "one we haven't done in quite a long time. Actually, it's almost the first song that Keith (Richards) and I wrote. We didn't do it at the time, we gave it to someone else, a young lady, to sing. But we're going to do it now, with a bit of help..."