Taylor Swift & Selena Gomez: Duet at Madison Square Garden!

Selena Gomez and Rock & Roll Hall of Famer James Taylor sandwich in Taylor Swift backstage at Madison Square Garden on Tuesday (November 22) in NYC.

The 19-year-old singer and actress surprised fans by joining Taylor, 21, on stage during her Speak Now world tour. The two sang Selena‘s “Who Says” – the first time the pals have ever performed together!

James also showed up and sang “Fire and Rain” with Taylor, who shared it was her favorite song in fifth grade chorus class.

“I have so much to be thankful for this year. I’m leaving New York, replaying this tour in my mind. I love you all so much,” Taylor tweeted, while Selena wrote, “Performing at Madison Square Garden with my best friend was a highlight.”

FYI: Taylor sparkled in a black sequin mini dress by Jenny Packham while onstage.

25+ pictures inside of Taylor Swift and Selena Gomez performing together…