Taylor Swift is known for her surprise collaborations in concert, and she did not disappoint during her performance on Saturday at Gillette Stadium. Fans were thrilled when Carly Simon took the stage to duet with Taylor on Carly's iconic hit, "You're So Vain."
After the show Taylor tweeted, "Got to sing 'You're So Vain' with Carly Simon at Gillette Stadium tonight!!!!! Unreal. I could not possibly look up to her more."