Taylor Swift got to duet with the legendary Carly Simon on her massive hit song “You’re So Vain” at Gillette Stadium in Foxborough, Mass. on Saturday night.

Swift, known for writing about her past relationships, was excited to share the stage with Simon to sing the 1972 hit.

"Every girl out there will be thinking of someone when we're singing," Swift told MTV News backstage. She added of the song that it’s “the most direct way anyone has ever addressed a break-up.”

Simon added, “It's a song that really sort of developed that style of mine. And a lot of it was not knowing that I was developing that style, 'cause a lot of things happen by accident, don't you feel?" go which Swift agreed.

E! Online reports that Swift asked the crowd who they think the song is about before Simon appeared on stage, which has been a popular question since the song came out.

Those rumored to possibly be at the forefront of the song are Mick Jagger, Warren Beatty, Kris Kristofferson and Cat Stevens.

image: MTV screenshot