London UK - Olivia Rodrigo fans couldn't help but smile to see her O2 Arena Show in London where she reunited with industry vet and once-collaborator Lily Allen!

Liv and Lily performed together at Glastonbury in 2022 in a rousing performance of the 2008 smash F*ck You, which they dedicated to "the five members of the Supreme Court who have showed us that at the end of the day, they truly don’t give a sh*t about freedom" following Roe v. Wade being overturned.

The duo were back in action on Friday for an iconic team-up on the Driver's License singer's latest Guts World Tour stop.

"The best day of my whole career was when I got to sing with her a few years ago at Glastonbury," Olivia gushed to the crowd before introducing the Not Fair artist.

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"I absolutely adore her. Would you please give it up for Ms. Lily Allen!"

Together the women performed Lily's 2006 hit song Smile, sweetly hugging it out at the end.

"Been a while since i’ve sang at the O2. what a lovely crowd," the older singer wrote to Instagram with a couple of behind-the-scenes snaps.

"what a lovely crew. Thank you @oliviarodrigo x"

Olivia raved about her friend right back on Insta Stories, writing, "Last night at the O2 wit the coolest girl in the whole world" over a video of their performance.

Are you a fan of the Olivia Rodrigo and Lily Allen collab?