Paul McCartney plays 'Yesterday' with Kronos Quartet

Paul McCartney was joined by the Kronos Quartet during his performance of "Yesterday" at the Outside Lands festival on Friday.

The quartet, dubbed "classical music's own Fab Four" by Rolling Stone in 1987, are perhaps best known for their edgy collaborations with musicians like Tom Waits, David Bowie, Bjork and even the poet Allen Ginsberg.

According to Contact Music, the strings "perfectly complemented" McCarty's hit song which he usually plays as a solo act with nothing more than an acoustic guitar.