Billie Eilish surprised fans in Los Angeles by bringing Charli XCX on stage for a live performance of their Guess remix.

The Bad Guy singer thrilled the audience at the KIA Forum on Tuesday night with the duo’s first live rendition of their Grammy-nominated collaboration. The unexpected appearance was part of Billie’s ongoing Hit Me Hard and Soft world tour.

After the performance, Charli XCX shared a video of the energetic moment on Instagram, captioning it, "love u billieeeeee and hbd (happy birthday)!!!" The show occurred just a day before Billie celebrated her 23rd birthday on Wednesday.

The Guess remix was released in August 2024 as part of Charli’s remix album, Brat and It’s the Same but There’s Three More Songs So It’s Not, following the success of her hit album Brat. The track has garnered critical acclaim and is nominated for Best Pop Duo/Group Performance at the 2025 Grammy Awards.

Billie launched her Hit Me Hard and Soft tour in Quebec City, Canada, on September 29, 2024, to support her third studio album. The tour will wrap up in Dublin, Ireland, on July 27, 2025.