During her ‘Eras Tour’ stop in New Orleans on Saturday night, Taylor Swift surprised her fans with a performance with fellow pop diva Sabrina Carpenter, according to Billboard. “It’s been stuck in my head,” Swift teased as she was ready to perform a song by someone else during her acoustic performance, hinting that she was about to do something special.

Swift started playing Carpenter’s popular song Espresso on her guitar, much to the delight of the audience. “Is it OK if I call her, and you guys can say hi?” she inquired in jest after singing a partial version of the song. After that, Swift placed Carpenter on speakerphone and asked her how long it would take to get to the stadium.

Shortly after, Carpenter surprised the crowd by taking the stage. The two celebrities then started a playful mashup of Carpenter’s other smash song, Please Please Please, and Swift’s 1989 vault tune, Espresso.

Swift’s performance of Carpenter’s Espresso’s “I’m working late ’cause I’m a singer” to a sold-out audience at around 11 p.m. was one of the night’s highlights.

Additionally, check out Taylor Swift’s announcement that she will wrap off her tour by releasing her first book.

“She only gets one day off. She’s on tour. At the conclusion of their duet, Swift praised Carpenter’s commitment, saying, “This is crazy that she came to perform for us.” After Carpenter left the stage, Swift played a piano mashup of her songs “Hits Different” and “Welcome to New York” to end the evening.