AceShowbiz - Amy Winehouse was left red-faced after forgetting the words to her hit "Valerie" during a rare onstage performance in London on Tuesday, July 6. The singer joined her "Valerie" collaborator Mark Ronson at an intimate gig at the British capital's 100 Club as the producer launched his new band The Business Intl.

Ronson performed tracks from his upcoming album before Winehouse stepped onstage during the encore. The duo began their version of The Zutons' track, the final number of the night, but the singer stumbled through the first verse as she struggled to remember the lyrics.

The "Rehab" hitmaker has played live only a handful of times in recent years as she battles turbulent personal issues, including substance abuse problems and her split from husband Blake Fielder-Civil.