They looked like old friends sitting on a front porch for the umpteenth time. In fact Miley Cyrus even referred to Taylor Swift as “my best friend” after they finished a song on the Grammy stage this evening.

This marks the first ever duet for the music superstars. Let’s call it—love at first sound.

Their performance of the Swift-written “Fifteen,” with Swift playing guitar and Cyrus singing along, was one of the highlight of the Grammy night.

Ironically the performance came just before the Jonas brothers performed with Stevie Wonder. Both Cyrus (Nick Jonas) and Swift (Joe Jonas) had well-publicized relationships with their respective members of the bro-band.

The young ladies also made their way along the red carpet together, arm in arm as one another’s date.

Their new affiliation also brought out one of the big burning questions of the night: Why was Katy Perry carrying locks of both of their hairs in her clutch?

Perry showed the locks to Ryan Seacrest on the red carpet, regretfully without explanation.