Two pop stars metaphorically collided on Thursday, Aug. 15, when Taylor Swift invited Ed Sheeran onstage during the acoustic section of her “Eras Tour” at Wembley Stadium in London. Halfway through Swift’s performance of “Everything Has Changed” on guitar, she joked that something didn’t feel quite right.

Sheeran then appeared onstage to join her. Swift and Sheeran performed a mash-up of three songs: and Both “End Game” and “Everything Has Changed” are duets Swift and Sheeran sang on her past albums. “Thinking Out Loud,” from Sheeran's 'x' album, is one of his biggest hits and earned him a Grammy for song of the year in 2016.

Swift previously wrote about how much she loves the song. reports that in a since-hidden Instagram post in honor of Sheeran’s 25th birthday, Swift wrote that listening to “Thinking Out Loud” was one of the “highlights of my life.” “Looking back on the highlights of my life, there’s a moment I’ll never forget from a day in London about two years ago,” she wrote, adding she was buying ballet shoes when Sheeran met up with her.

“He walks in and says ‘You have to hear this new song. I think it’s the best one I’ve ever written.’” In her Thursday night performance with Sheeran, Swift continued to sing her friend’s praises.

Following their duet mash-ups, she told the audience that Sheeran is “one of my best friends.” “This is one of my best friends in the world to the point where I feel like he’s a.