Music-lovers who went to see Friday night's 'Howlin for Hubert' tribute concert to honor legendary Howlin' Wolf guitarist Hubert Sumlin got quite a treat when Keith Richards and Eric Clapton shared a stage to pay homage to the Chicago blues great.

At about midnight, Clapton had just finished the classic song 'Forty Four' at New York's Apollo Theater when the Rolling Stones' fabled guitarist strolled out with no introduction -- but he didn't need one. Fans recognized Richards on sight, and rewarded him with thunderous applause as he gave Clapton a hug and the two revered musicians launched into Wolf's 'Going Down Slow' as well as 'Little Red Rooster' and 'Spoonful.'

Richards hasn't had a major musical appearance since the last Rolling Stones' tour five years ago, but those at the Sumlin concert reported the time off didn't seem to have affected 68-year-old's guitar prowess. "It’s good to be back," Richards told the crowd with a laugh. "Goddamn, it’s good to be back."

The show was planned while Sumlin was still alive as an 80th birthday celebration, but after his death from heart failure late last year, performers decided to keep the date but turn it into an epic benefit concert instead, with the proceeds going to the Jazz Foundation of America.

And if you're a blues lover, what a concert it was -- the lineup boasted Buddy Guy, Billy Gibbons, Warren Haynes, Jimmie Vaughan, Kenny Wayne Shepherd, Elvis Costello and many others.

Richards was a long-time fan of Sumlin's -- he played on the bluesman's 2006 album 'About Them Shoes' -- and after Sumlin passed away, Mick Jagger and Richards paid for his funeral expenses, with Jagger saying at the time, "Hubert was an incisive yet delicate blues player ... He was an inspiration to us all."