Watch: Harry Styles + Kacey Musgraves cover Shania Twain's 'You're Still The One' together live.

Kacey Musgraves is currently on tour in America with Harry Styles as his opening act, and last night joined him on-stage during his set to cover Shania Twain's classic 'You're Still The One' live together last night at Madison Square Garden.

Watch fan-filmed footage of the performance below...