Taylor Swift‘s surprise song set went from celebratory to somber in Stockholm on Sunday (May 19).

For the acoustic section of her third Eras show at Friends Arena, Swift was all smiles as she dedicated a medley to Sweden’s Max Martin — and then full of melancholy for the live debut of “How Did It End?” from The Tortured Poets Department: The Anthology.

First up was Swift’s pop medley on guitar in honor of the “genius pop songwriters and producers” she’s said she’s worked with. “Max is actually here tonight,” she pointed out, revealing that she was going to play “what I am calling the Max Martin Medley.”

She started with “Message in a Bottle,” the first song she ever wrote with Martin, which was penned with Martin and Shellback for her 2012 album Red but didn’t get released until 2021’s Red (Taylor’s Version). “Message in a Bottle” is a vault track on Swift’s rerecorded version of the collection.

“How You Get the Girl” and “New Romantics,” both from the 1989 era, completed the upbeat medley that Swift looked elated to play at the third of a trio of shows in Stockholm this weekend.

But the joyful mood shifted when Swift sat at her piano and told the crowd, “I’ve never performed this one live before,” and then went straight into “How Did It End?” from Tortured Poets. Featured on the Anthology edition of the star’s new album, “How Did It End?” is a stirring ballad that questions the collapse of a relationship.

While Swift was on stage performing in Stockholm, Billboard reported that The Tortured Poets Department has locked its fourth consecutive week atop the Billboard 200.

After wrapping a three-day stint in Stockholm, she’ll be taking her Eras Tour to Lisbon, Portugal, for a set of concerts next weekend.

Watch clips of “How Did It End?” and Swift’s medley of “Message in a Bottle,” “How You Get the Girl” and “New Romantics” below. Check out a complete list of all the other surprise songs Swift has performed on The Eras Tour so far here.