Swift surprised fans by appearing with the HAIM sisters on stage at London’s O2 Arena for a rendition of their collaborative track "Gasoline" and a mash-up of Swift’s own song, "Love Story.

After joining the band, Swift said: “I haven’t been on stage in a very long time." It’s nice... it’s nice, it’s very nice [to be back]. When I heard my girls were playing in London at the O2, I thought, "I’m going to have to see that." And it looks like there are about 20,000 other people who also thought that.

So we had a thought. If we were to do some sort of mash-up, we could possibly get you to sing the loudest you have sung all night – which is a big challenge because you have been singing very loudly – extraordinary work. "

HAIM opened for Swift during her '1989’ world tour in 2015 and have been frequent collaborators with her in the past. In 2020, HAIM appeared on Swift’s album "Evermore" on the track "No Body, No Crime".

Check out the footage NME captured of the moment below, along with other fan-shot videos and the full setlist:

HAIM – London O2 Arena setlist:

Now I’m In It.

'I Know Alone’

Up From a Dream

Don’t Save Me

'My Song 5’

'Want You Back’

'3 AM’

I’ve Been Down

Gasoline/Love Story" – with Taylor Swift

'Leaning On You’

Hallelujah

'Man From The Magazine’

'FUBT’

Los Angeles

'Don’t wanta’

'Forever’

'Summer Girl’

Encore

'The Wire’

'The Steps’