Michael Bublé is one smooth crooner, but he may have finally met his match at a recent concert in Duluth, Ga.

In the video clip below, Bublé is seen handing his microphone over to a fan to sing Sinatra's 1954 hit, "Fly me to the Moon."

"Want me to help you?" the Canadian star asks the fan, who is dressed in a navy suit. The eager singer, Andrew Zarrillo, replies, "No, I'm fine." When he finally starts singing, Bublé is stunned and even gets up and runs away.

Zarrillo, who uploaded the video of the performance on YouTube, wrote in the clip's description: "Everyone thought it was scripted but it's a totally impromptu moment!"

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