The Grateful Dead’s Bob Weir joined Paul Simon onstage during the latter's closing set at the Outside Lands festival in San Francisco last night.

After reminiscing about hanging in the city’s Haight-Ashbury district during the '60s, along with recalling his appearance at the Monterey Pop Festival in 1967, Simon surprised the thousands of fans in attendance by welcoming Weir onstage for a performance of Simon & Garfunkel's “The Boxer.”

You can watch fan-shot video of the duet below.

The collaboration was the biggest highlight in a set that featured hits from throughout Simon’s storied career.

The music icon took the stage as day turned into night, delivering a multitude of classic tracks, including “You Can Call Me Al,” “Diamonds on the Soles of Her Shoes,” "50 Ways to Leave Your Lover" and “Bridge Over Troubled Water.” Throughout the performance, Simon displayed the talent and charm that's made him one rock's most respected artists for more than five decades. His final song of the evening, an earnest rendition of "The Sound of Silence," was the icing on the proverbial cake.

The massive audience watching Simon’s set at Outside Lands was comprised of teens, baby boomers and everyone in between, providing further evidence of the singer’s enduring appeal across generational lines.

Simon retired from touring in 2018, following a successful farewell trek. But he left the door open for occasional one-off performances such as this festival-headlining set. Rather than banking his paycheck for the event, Simon donated his earnings from Outside Lands to local environmental nonprofit organizations.

Even though it was Simon’s first time performing at the festival, his music has been featured there in earlier years. Pop singer Lorde memorably covered “Me and Julio Down by the Schoolyard” alongside Jack Antonoff in a 2017 performance at Outside Lands, and singer-songwriter Vance Joy also covered Simon during that year’s fest, delivering a joyful rendition of “You Can Call Me Al.”

Simon's performance at the 2019 edition of Outside Lands capped an eclectic weekend of music in Golden Gate Park that featured artists from a wide variety of genres.

Earlier at the fest, Blink 182 delivered and energetic set of pop-punk hits, including a brief cover of the Ramones' “Blitzkrieg Bop”. Elsewhere, Irish singer-songwriter Hozier serenaded the crowd with his blend of jazz- and rock-inspired tunes, highlighted by his 2013 hit “Take Me to Church.” The Lumineers, Twenty One Pilots, rapper Childish Gambino and electronic duo Bob Moses were among the festival’s other stand-out performers.

 

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