Thanks to one lucky fan, who happened to be driving through Los Angeles at the same time as Perry and Corden on Monday, we know they're going to belting out a rendition of Perry's hit "Dark Horse."
"Only in LA #katyperry #carpoolkaraoke," Instagram user nycdarren captioned a video he posted showing the singer -- rocking a super short blonde 'do and a blue, button-down collared shirt -- crooning her single out the window of Corden's SUV.
"It's going to be great. I'm so excited. We haven't shot it yet, we're shooting it next week. I know it's gonna be amazing," Corden shared. "I'm so looking forward to just being in her orbit for just a little bit of time. You know, I'm a huge fan."