Paul McCartney's stop in Seattle last night included a surprise appearance from former Nirvana bassist Krist Novoselic, who joined in for a performance of the Beatles classic "Helter Skelter."

You can watch the pair's collaboration via the fan-shot footage above, which captures the latest in a series of curveballs from McCartney over the first few days of his current One on One Tour. As previously reported, McCartney debuted a revamped set list for the tour's opening night on April 13, bringing a handful of songs out of storage — some of which were making their live solo debut.

The Beatles tracks "A Hard Day's Night" and "Love Me Do" both made their first appearance in a McCartney show on April 13, and he also incorporated a number of songs he hadn't performed live in years, including the Quarrymen's “In Spite of All the Danger"; "You Won’t See Me,” which made its live U.S. debut; and “The Fool on the Hill,” “Here, There and Everywhere,” “I’ve Got a Feeling” and “Letting Go."

McCartney previously collaborated with Novoselic and ex-Nirvana drummer Dave Grohl for a benefit single, "Cut Me Some Slack," in 2012. That song made its debut during the 12-12-12 Hurricane Sandy concert and was later heard during Grohl's documentary Sound City.

"We walked in; we jammed the song. It just came out of nowhere. The best songs happen that way,” Grohl later explained. “We recorded it live and put a vocal over it and that was it. It was three hours and it was perfect."

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