Charli XCX's set at Lollapalooza on Sunday (August 6) included a cover of Spice Girls' anthem "Wannabe" alongside surprise guest Halsey, and the Chicago crowd was absolutely living. 

Prior to welcoming her future tour mate to the stage, Charli XCX asked the obvious: "You guys like girl power, right? [I] said, 'Do you like girl power? Sing along if you know it." Atop what sounded like a pre-recorded studio version, the pop star handled the opening verse before Halsey arrived on the scene, offered up her contributions to the '90s classic and even busted out some of the iconic girl group's dance moves. Elsewhere in the set, Charli XCX confirmed that her recent single, "Boys," will be off a forthcoming album, so expect the star to hustle hard in the coming months. 

You'll likely see more of these two when Halsey kicks off her upcoming fall tour, which will see Charli and PartyNextDoor serve as opening acts. The North American trek is scheduled to kick off September 29 and wrap November 22. 

I'm not having a slumber party with @charli_xcx but I #wannabe. Also idk how to crop photos. 💤🌸

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