Halfway through Paul McCartney's set Saturday at Desert Trip, the rocker is accompanied by Neil Young - who introduced him at the Indio, California fest - to play a pair of Beatles songs with him, "A Day in the Life" and, for the first time at all, "Why Don't We Do It in the Road?"

Describing Young as "a really good friend of ours that I've known through the years" - it was Young who initiated McCartney as a solo artist into the Rock and Roll Hall of Fame in 1999 - the two rock icons first doled out the Sgt. Pepper'scloser, which Young had performed in the past with the former Beatles bassist. This song covers of "A Day in the Life" segued into an unanticipated interpretation of John Lennon's anthem "Give Peace a Chance."

"I'm going to take a moment to drink this in for myself," McCartney said, walking on the stage to look out on the sea of faces stretching to the purview. His set was a smooth mix of Beatles classics and solo songs from across generations, performed with normal good cheer, his voice in splendid form. "Let Me Roll It" even alleviated into an instrumental wind-out on Jimi Hendrix's "Foxy Lady."

Promise of the two includes Willie Nelson's sons, Lukas and Micah Nelson, a harmoniously rooted for Young in his yearly Farm Aid concerts with Willie. It's been a lively concert, as the quintet brings understanding and youthful discovery to Young's music.

The central event in Young's set was dynamite "Down by the River," clocking in at over 22 minutes. Fans began singing from the opening lines, but were soon overwhelmed by the power of the 1969 guitar epic. Young cut and bashed at his guitar, the sound is keen and nearly out of control, lengthened out as always but still noisy and erratic, never precisely the same way twice. Lukas Nelson took a wild inclining solo, soaring and crashing. "Too much," Young said into mic, then uttered "too much."