Credit: Frederick M. Brown/NBC via Getty

Now this is the duet we have been waiting for! At the iHeartRadio Music Awards on Sunday when Madonna came to the stage to sing "Ghosttown" from her new album Rebel Heart, she wasn't alone: The one and only Taylor Swift appeared by her side to accompany her on the guitar.

The performance started with Madonna—in a Greg Lauren leather corset over a white collared dress shirt, fingerless gloves, fishnet stockings, and knee-high leather boots—sitting on a stool and singing. You can see someone sitting behind her, but only from the back. The camera then pans around and reveals Swift's face. Eventually Madonna struts down the stage to belt out the tune and Swift—who followed Madonna's style lead with a Greg Lauren corset, thigh-high stockings and tall leather boots—joins her and rocks out on her acoustic guitar.

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It was likely an overwhelming moment for Swift judging from her reaction when Madonna referred to her in an interview earlier this year. "It's good to have princesses (of pop)," Madonna told Australia's Today show in January. "It means there's lots of pretty dresses around. I like Taylor Swift. I think she writes some really catchy pop songs, I can't get them out of my head." Swift's response to the major props? "Thanks now I'm dead," she wrote on Tumblr.

Swift shared her feelings about the experience on social media. She posted a photo of the duo with a quote from Madonna's "Ghosttown" and also shared a snap of the performance with the caption, "I might be okay but I'm NOT FINE AT ALL #MyFangirlLife":

On top of performing with her idol, Swift had an eventful night: She won the awards for best lyrics for "Blank Space," song of the year for "Shake It Off," and artist of the year, which Madonna presented to her. She also had a grand time hanging out with Justin Timberlake.

Watch Madonna and Taylor Swift's dynamic performance at the 2015 iHeartRadio Music Awards below.