Haim brought out Taylor Swift as a special guest at their sold-out show at London's O2 Arena tonight, performing a mash-up of 'Gasoline' and 'Love Story' onstage together.

? Taylor Swift just posted on TikTok backstage getting ready with @HAIMtheband in London tonight ?https://t.co/xpHkVPrDgH pic.twitter.com/jmgSnoaDQY

— Taylor Swift Updates (@SwiftNYC) July 21, 2022

Watch fan-filmed videos of the performance below...

TAYLOR SWIFT JUST CAME OUT HAIM pic.twitter.com/tg5zRaq3Fw

— Zakk (Taylor’s Version) ? (@thinkzakkIknows) July 21, 2022

Casual Taylor Swift cameo in the @HAIMtheband concert! pic.twitter.com/lvuI2KfLKX

— Ryan Bailey (@RyanJayBailey) July 21, 2022

Not @taylorswift13 coming out onstage with @HAIMtheband ?? pic.twitter.com/UUB2wZrbLd

— Hayley Minn (@hayleyminn) July 21, 2022

Watch: Haim and Taylor Swift perform 'Gasoline' and 'Love Story' mash-up together in London.