SZA is pulling out all the stops on her SOS tour. Tonight (March 4), she performed the first of two New York City shows at Madison Square Garden. During her tour, a special guest made a surprise appearance on stage.

In a clip shared by The Hollywood Reporter, SZA brought out Phoebe Bridgers for a performance of “Ghost In The Machine” from SZA’s sophomore album, SOS. Surprising the audience, Bridgers performed her verse of their collab, alongside SZA.

Tonight marks the first time Bridgers and SZA have performed the song live together.

In an interview with NME, Bridgers revealed how the collaboration came together just days before SOS was supposed to drop.

“She just hit me up. She just sent me a DM, and then it all happened so fast,” said Bridgers. “I wasn’t really used to that in that pop world, because vinyl isn’t so much of a consideration until way later. It’s just like, ‘Do you want to be on this record? OK, it’s out next week.’ It was so recent, which I really like. I like that turnaround time. Personally, I sit on stuff for so long and it takes me years to make albums. I like seeing someone else’s world from that angle.”

Check out a clip of the “Ghost In The Machine” performance above.