Bob Weir Sits in with Norah Jones at Outside Lands

Towards the end of her set at Outside Lands on Saturday, Norah Jones surprised just about everyone when she brought out the Grateful Dead's Bob Weir to assist on a cover of the Dead's "It Must Have Been the Roses." Weir was not scheduled to perform at the festival otherwise, although he was seen on Friday night enjoying a set by Neil Young and Crazy Horse.

"Everybody in Norah's band are just huge Deadheads," guitarist Jason Abraham Roberts told Rolling Stone, directly before taking the stage. "We've actually been playing 'It Must Have Been the Roses' almost every night, because we were like, 'We have to play a Dead song.'"

Roberts met Weir last week when they both performed in Move Me Brightly, an all-star celebration of what would have been Jerry Garcia's 70th birthday, which was filmed at Weir's TRI Studios. After the show, Weir told Roberts that his daughter is a huge Norah Jones fan and that he'd like to take her to Outside Lands to see Jones play. When Roberts invited Weir to sit in – at Jones' suggestion – Weir simply responded, "What guitar should I bring?"

"We're kind of freaking out about it," says Roberts. "Playing a Grateful Dead song, in Golden Gate Park, with a member of the Grateful Dead? It’s pretty crazy."

While Weir headlined Outside Lands in 2010 with his current group, Furthur, the Grateful Dead once staged a number of historic concerts in San Francisco's Golden Gate Park, where Outside Lands is now held.