American music sensation Billie Eilish brought out some special guests at an intimate, 1800-capacity London gig: indie royalty boygenius and singer-songwriter Labrinth joined the 21-year-old onstage Tuesday night.

The gig took place in Camden at the Electric Ballroom, a surprise show following Eilish's headlining Reading & Leeds set this past weekend. Tickets sold out immediately after its announcement on Saturday, and some fans even camped outside to try to get a chance at barricade.

Midway through the set, Eilish brought out the Euphoria composer Labrinth to massive fanfare to play their collaboration 'Never Felt So Alone'. Two songs later she told fans to lower their phones as she told them who the next guest would be in order to see their excited faces when the indie trio, made up of Phoebe Bridgers, Lucy Dacus and Julien Baker, took to the stage. They helped her perform her hit ‘When The Party’s Over’, and Eilish professed her love for them as they departed. "I’m in love with all three of them. Truly,” she announced.

Another angle of boygenius performing When The Party’s Over with Billie Eilish at her show tonight!! pic.twitter.com/v3vO7CLSd3

— phoebe on tour (@bridgersontour) August 29, 2023

boygenius' appearance comes just one day after their euphoric Irish show at Kilmainham on Monday night. They visited Ireland as the last stop on their European tour and are set to take a month off touring before kicking off their massive headlining US tour this fall.

The cameos are an interesting development before Eilish's set this weekend at Co. Laois' Electric Picnic festival: speculation is brewing as to whether Eilish might bring out more special guests during the gig.

Other headliners this weekend include Niall Horan, Fred again.., The Killers, Paolo Nutini, and The Script. Tickets are sold out, but you can follow Hot Press' coverage of the highly anticipated event on social media.