Photo via Crossroads’ Twitter

Keith Richards made a surprise appearance with Eric Clapton at the Crossroads Guitar Festival last night. The Rolling Stones guitarist took the stage without any formal introduction at the start of Clapton’s headlining set and led Slowhand and his band through “Key To The Highway” and “Sweet Little Rock and Roller.” Clapton’s set closed out his two-night benefit concert at New York’s Madison Square Garden.

The evening’s musical offerings started at 7:30 PM, almost four hours earlier, when Clapton welcomed Crossroads veteran Sonny Landreth and his band. As he introduced Landreth, Clapton described the guitarist as someone who “always sends back his card the following day” when invited to play Crossroads. Clapton also admitted that he decided to move Crossroads inside this year since “you never know with the weather.” At the end of Landreth’s 20-minute set, Derek Trucks emerged for the first of several cameos.

In order to keep the show moving along, two acoustic performance spaces were set up on either side of the Garden’s grand stage. Clapton’s longtime guitarist Doyle Bramhall II offered the evening’s first “tweener” performance and brought out John Mayer to play an acoustic song that his father wrote for Stevie Ray Vaughan. Their duet served as a fitting introduction to the evening’s second main act, Stevie’s brother Jimmie Vaughan. The veteran Austin guitarist charged through a 20-minute set of electric blues and showcased both his current touring partner Lou Ann Barton and fellow Austin guitarist Dave Biller.

While most of the evening was devoted to boomer-era classic rock and new blues hotshots, Clapton handpicked a few left-field acts for this year’s Crossroads. One of those acts was guitarist Blake Mills, who co-founded the Dawes predecessor Simon Dawes and spent time as a member of Fiona Apple’s band. Clapton first heard Mills’ music in a commercial, but mistook him for Derek Trucks. Bringing things full circle, for the second song of his acoustic set last night, Mills nudged out Trucks to play guitar on The Drifters’ beach music classic “Save the Last Dance for Me.”

As Trucks left the stage, his wife Susan Tedeschi emerged for a surprise performance with Los Lobos. The Tedeschi Trucks band leader sang with Lob Lobos on their own “Burn It Down,” before handing over the stage to the veteran rock band. Los Lobos offered one of the evening’s most energetic performances. They brought out some guests throughout their 25-minute mini-show too, including Robert Cray and Clapton, the latter of whom played guitar on “Tin Can Trust.”

One of the big question marks surrounding last night’s show was whether or not The Allman Brothers Band would perform. The veteran jamband returned to the Garden for the first time since 1986 on Friday night as part of Crossroads, so many wondered if they’d return for an encore appearance yesterday. Instead of a proper set, three members of The Allman Brothers Band offered an acoustic segment. Actor/Blues Brother/House of Blues co-founder Dan Aykroyd introduced ABB guitarist Derek Trucks and Warren Haynes with a colorful history lesson that detailed the group’s generational ties. He also noted that Trucks was named after Clapton’s Derek & the Dominos’ project, which featured ABB founder Duane Allman.

Haynes and Trucks ran through an acoustic take on the latter day Allman Brothers Band tune “Old Friend.” Then, Gregg Allman joined the guitarists for an emotional reading of “The Needle and the Damage Done,” a song which reflected the evening’s theme of substance-abuse prevention. Finally, Allman strapped on an acoustic guitar and joined Haynes and Trucks for his signature song, “Midnight Rider.”

Shifting things up once again, after an acoustic Allmans interlude, Vince Gill emerged for a country set. During his set, Gill said, “It’s one of the greatest things that ever happened, getting this invitation from Eric Clapton.” He also brought along fellow country star Keith Urban and guitarist Albert Lee for his 30-minute country-fried set. Foreshadowing things to come, they also covered The Rolling Stones’ “Tumbling Dice.”

The rest of the evening was devoted almost exclusively to the blues. Keb Mo and Taj Mahal, representatives form two generations of blues guitarists, ran through a brief duo set that included Robert Johnson’s “Walking Blues” on one of the festival’s side stages. Newly anointed blues master and Austin guitarist Gary Clark Jr., who considers his last Crossroads appearance a career breakthrough, stepped into his new role as a marquee performer with a prime electric slot. Jeff Beck and his band charged through 25-minutes of classic blues-rock with Beth Hart on vocals and Buddy Guy offered a lovely, rambling version of his “74 Years Young” on one of Crossroads’ “b-stages.”

Without much fanfare, Richards, Clapton and Clapton’s backing band appeared shortly before 11 PM for the evening’s final segment. Richards showed off both his vocal abilities and his guitar prowess and took on the role of event MC. He remarked how much he enjoyed being back at Madison Square Garden and told the audience it was time for some “rock-and-roll” before “Sweet Little Rock and Roller” (Roger Waters was also spotted backstage but did not perform.)

The parade of guests continued as Richards faded into the wings. Band guitarist and songwriter Robbie Robertson, the most reclusive of the evening’s performers, emerged for his new original “He Don’t Live Here No More.” (Clapton appears on the studio version of the song on How To Become Clairvoyant.) He remained onstage and sang lead on the Band-adopted Bob Dylan classic “I Shall Be Released,” which Robertson dedicated to his friends who “are no longer with us.” His remarks held extra significance as the calendar inches toward the first anniversary of his estranged bandmate Levon Helm’s passing.

Though guitarist Andy Fairweather Low joined Clapton for “Gin House,” Slowhand owned the rest of the evening. Clapton and his road band kicked off their portion of the show with “Got To Get Better In A Little While,” and they also offered the classic blues workout “Crossroads,” “Little Queen Of Spades,” Cream’s “Sunshine Of Your Love” and their usual show-closing cover of Joe Cocker’s “High Time We Went.” During the final song, most of the evening’s performers—with the notable exception of Richards and Allman—emerged for an extended jam. Clapton thanked the audience and remarked that he hoped to see them again, presumably at the next Crossroads event.