Eric Clapton hosts star-studded Crossroads festival

Eric Clapton's Crossroads festival has become the mecca for riff worshippers, so it was appropriate that guitar deity Keith Richards made a surprise appearance to perform with Clapton.

The Rolling Stone received perhaps the most sustained standing ovation of the night as he joined his old pal toward the end of Crossroads, a two-night concert festival at Madison Square Garden that brought together a dazzling array of guitar masters, from John Mayer to Jeff Beck to legends like Buddy Guy, and of course, Clapton and Richards.

Richards -- whose Stones announced another tour earlier this month -- flashed his typical wry smile to the crowd before joining Clapton in playing the blues standard and Clapton favorite "Key to the Highway. "

"Now we're gonna rock it up," Richards said before launching into "Sweet Little Rock N' Roller."

Richards' appearance was only the beginning of Clapton's hour-plus-long set, which included hits like "Crossroads" and "Little Queen of Spades." It also featured other special guests, like Robbie Robertson, who sang the classic "I Shall Be Released."

"I just want to say it's an honor to be here in honor of Crossroads and Eric Clapton," Robertson said.

Crossroads Guitar Festival, which benefits Clapton's Crossroads Centre for substance abuse in Antigua, has been held every three years since 2004; this Friday and Saturday was its first at Madison Square Garden.

The show lasted almost five hours, with each performer showcasing his particular brand of wizardry on the instrument. (All the headliners were men, though there were a few women as supporting players in the program.)

Clapton joined Los Lobos and Robert Cray early on, and Warren Haynes and Derek Trucks played an acoustic set and brought out Gregg Allman. Keb' Mo' and Taj Mahal paid tribute to the blues in their acoustic set, while newcomer Gary Clark Jr. had the crowd on its feet throughout most of his electrifying set, which was followed by another fiery set, this one by Jeff Beck.

Other highlights were a performance by blues great Buddy Guy and a set from Vince Gill, Keith Urban and Albert Lee.

"It's one of the greatest things that ever happened, getting this invitation from Eric Clapton," Gill gushed onstage.

The night ended with just about all the evening's performers coming back on stage for a jam session with Clapton.

"See you in three years," Clapton told the crowd before exiting the stage.

Clapton, 67, recently told Rolling Stone that the traveling from touring takes a toll: "The bit onstage, that's easy. If I could do that around my neighborhood, that would be great. You have guys in Texas that play their circuit, and it keeps them alive. But for me, the struggle is the travel. And the only way you can beat that is by throwing so much money at it that you make a loss."

He added: "So the idea is I'm taking a leaf out of JJ [Cale]'s book: When I'm 70, I'll stop. I won't stop playing or doing one-offs, but I'll stop touring, I think."