Paul McCartney was joined onstage in Seattle by former Nirvana bassist Krist Novoselic, who helped out during the encore performance of "Helter Skelter."

Novoselic and Paul both played bass and the former also added vocals.

The performance came during Macca's ongoing One on One tour.

McCartney and Novoselic previously hooked up with Dave Grohl and Pat Smear to perform at a handful of gigs and record the original cut "Cut Me Some Slack."

Sir Paul's One on One tour picks up with two dates at Vancouver's Rogers Arena on April 19 and 20.

The trek then heads to Little Rock (April 30) and Sioux Falls (May 2), before wrapping the U.S. leg with two dates at Minneapolis' Target Center on May 4 and 5.