The dance music star was entertaining the crowd with a DJ set during the Los Angeles festival on Sunday (23Aug15) and the Royals hitmaker came onstage as he played his remix of her single Tennis Court.
She admitted the appearance was even a surprise to Flume, later writing on Instagram.com, "I had never seen harley play live before so I went down to fyf tonight to watch his set, and basically he played his awesome tennis court remix and I kinda got peer pressured into sneaking up onstage and surprising him for a dance party in front of 20,000 people lol (laugh out loud).
"He had no idea it was happening, I decided to go up literally 20 seconds before I did. and it was FUN being onstage at a festival again having a silly dance!! here's to cool friends and funny surprises."
The New Zealander was not the only surprise appearance of the weekend - headliner Kanye West brought Rihanna onstage for two songs on Saturday (22Aug15).