Young walked out onstage during Lofgren's fourth appearance at his charity festival and joined the guitarist for Grin track Believe to rapturous applause.

Bruce Springsteen's E Street Band sidekick first appeared on Young's 1970 album After the Gold Rush, when he was a teenager. The two old pals last performed Believe together in 1991.

Lofgren then joined Young and Promise of the Real on piano for their nine-song set.

This year's Bridge School gig also featured performances by the reunited Dixie Chicks, St. Vincent, Gary Clark, Jr. and Sheryl Crow.