Tonight was the opening show of Taylor Swift’s Reputation Tour. Joining Swift as promised at the Glendale, Arizona show was Charli XCX, who debuted a new track during her set. It’s reportedly called “5 in the Morning.” “This is a brand new song,” Charli told the crowd. “I’ve never played it before, ever.”

Camila Cabello is also a supporting act on Swift’s tour. During Swift’s set, Charli and Camila came on stage to perform “Shake It Off.”

Last year, Charli dropped off two mixtapes—Number 1 Angel and the PC Music-produced project Pop 2.

This article was originally published on Monday, May 8 at 10:57 p.m. EST. It was last updated on May 9 at 1:04 a.m. EST.