Taylor Swift surprised London’s O2 Arena by performing with Haim and it’s safe to say, the Swifties are not calm.

The American pop queen has been keeping a pretty low profile lately, and we can’t say we blame her for enjoying the downtime following the success of her lockdown albums and re-recordings of her existing catalogue.

But, in true T Swizzle style, she always pops up when you least expect it, and that’s exactly what fans were treated to on Thursday night when they wen to see what they thought was only a Haim gig in the capital.

The three sisters – Estee, Danielle, and Alana – are currently on their One More Haim Tour, and returned to the UK following an epic set at Glastonbury Festival.

Naturally, the crowd erupted into screams when the Blank Space hitmaker walked out to perform a killer mash-up of Haim hit Gasoline and Taylor’s country tune Love Story.

‘Wait, you guys, we’re in London, so we can’t play in London without bringing out a special guest’, the sisters started teasing.

‘Not only is this person that I’m about to bring out the most incredible singer, songwriter, producer, f*****g amazing person all around, she’s one of our close friends. So, O2 Arena, will you please welcome to the stage, Taylor Swift!’, they added excitedly, before the venue lost every ounce of chill.

The foursome looked ridiculously cool in matching black outfits, with the Haim sisters donning their signature black bikini tops and trousers.

Taylor, meanwhile, opted for a black crop top and a pair of high-waisted leather trousers, looking like the ultimate rock chic.

She swept her hair back into a braid and, of course, wore her trademark red lip.

After their performance and before leaving the stage, the friends shared an adorable group hug, with Taylor beaming from ear to ear as she waved fans goodbye while making her exit.

Taylor later posted a hilarious video to her TikTok account which showed the singers getting ready to hit the stage.

She added a children’s Copycat song in the background, poking fun at how she was copying their outfits.

This is by no means the first time the Haim trio have performed with Taylor, oh no, as they are longtime pals.

Estee, Danielle, and Alana actually joined Taylor as special guests for her 1989 Tour back in 2014, also collaborating with Nelly for a rendition of Hot In Herre.

On Taylor’s Grammy-winning album Folklore, Haim also feature in backing vocals on No Body, No Crime, with Estee in particular getting a namecheck in the lyrics.

‘Este’s a friend of mine, we meet up every Tuesday night for dinner and a glass of wine’, Taylor sings in the song inspired by her love for crime thrillers.