Taylor Swift debuts 'thank you aIMee' live, sings 'Castles Crumbling' with Hayley Williams in London

London is a “special” place to bring The Eras tour, Taylor Swift said during her acoustic set at Wembley Stadium on Saturday night (June 22).

In the second of three shows this weekend, the pop star decided to perform a song she had never performed live before. He also welcomed Hayley Williams to the stage for a duet.

“We have to play at Wembley eight times this summer. When I think about that, you just think about being thankful and grateful,” Swift told the crowd, showing their appreciation for their support. (She has her three shows in London this weekend and will return to Wembley for a further five shows later this summer, from August 15-20.)

“On the other hand,” commented Swift, who was set to perform the first of two surprise song performances of the night, “it really makes me think about how every time someone speaks – it makes me work even harder.”

“I've never played this before. Wish me luck,” he said, then launched into “thank you aIMee” on acoustic guitar, from Section The tortured poets: The Anthology. It marked the first live performance of the track in which she sings, “All that time you were throwing punches, I was up to something”/ And I can't forgive the way you made me feel/ She screamed, “F — you, Amy” into the night sky as the blood was gushing out'/ But I can't forget the way you made me heal'.

“I don't think you've changed much/ And so I changed your name and any real defining clues/ And one day, your child comes home singing”/ A song that only the two of us will know is about you. he adds in a later verse.

Swift performed “thanK you aIMee” as a mashup with Speak now“Mean,” another song about how he triumphed over the naysayers.

To top off that moment on Saturday night, he brought out Hayley Williams (who had opened the show with Paramore earlier) for a live duet of “Castles Crumbling,” their collaboration from Speak Now (Taylor Edition) blurred. Swift and Williams sat side by side at the piano as they sang.

Swift recalled the last time they played live together: on The Speak Now tourwhen she welcomed Williams onstage to perform Paramore's “That's What You Get” with her at a 2011 Nashville date.

Watch clips of Swift's surprise song from night two at Wembley below. Stay up to date with the full list of surprise songs played on The Eras tour here.