Taylor Swift Performs Ex Calvin Harris' 'This Is What You Came For' During First Performance in a Year

The 26-year-old singer opened her Austin, Texas, show with a fierce performance of 'New Romantics.'

Taylor Swift has officially returned to the stage -- performing the song she wrote for her ex-boyfriend, Calvin Harris, no less!

The 26-year-old singer made her big return during a one-night only performance at the Formula 1 U.S. Grand Prix in Austin, Texas, on Saturday. It was Swift's first concert since ending her 1989 World Tour in December, and she did not disappoint.

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In typical Swift fashion, the GRAMMY-winner took the stage in a sparkly black ensemble that showed off her long stems, a swipe of red lipstick, and a sparkly choker, all while appearing in a plume of smoke.

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"Welcome to F1 on a Saturday night!" she yelled out to her audience of over 100,000 as she opened the show with "New Romantics."

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The singer then followed up with a host of fan favorites, including a solo, acoustic version of "Fifteen," "You Belong With Me" on the guitar, "I Knew You Were Trouble," "22," "Blank Space," and "Style," all withing the first 20 minutes.

The night's biggest surprise, however, came when Swift performed "This Is What You Came For," the song she wrote for Harris and Rihanna.

"As a songwriter, the most rewarding feeling in the world is writing something and then having a crowd sing it back to you, because they know the words. It’s the coolest thing in the world," she told the crowd before jumping into her solo piano rendition of the electronic hit. "And I've never played this song live before, but you know it. Maybe you could sing along, and then I could get to know what that feels like to hear it sung back to me."

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Never seeming to take a breath, she played a cool mashup of "Bad Blood" and "We Are Never Ever Getting Back Together" in front of a 1989 backdrop, a remix of "Wildest Dreams" and "Enchanted," and sang "Holy Ground," "Love Story," "Out of the Woods," and "Sparks Fly."

The singer's only pause seemed to come from a short "tissue break."

"Of course, you play one show in one year and you get a cold one time, and it's before that one show. That's the way life works," Swift said, apologizing to her fans for interruption.

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Towards the end of her set, Swift joked, "You have been the best crowd of 2016" and warned the Formula 1 drivers not to text and drive. She then asked the crowd if they wanted to dance before closing with "Shake It Off" and a huge fireworks finale.

While only time will tell if Swift's performance will be followed by a midnight release of a new album, we do know the singer has been in the studio. She did say on stage, however, that the Austin show would be her only live concert in 2016.

It was Swift's pal Gigi Hadid who first let it slip that the singer was working on new music, while speaking with ET's Carly Steel at New York Fashion Week last month.

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"She's obviously such a great friend, and you know she is starting to go back to work in the studio again, and really made time to be here for me, and I am so grateful for that," the 21-year-old model shared.

See more in the video below.