Sometimes talent is hiding in the most unsuspecting places.

That’s what Tony Russo, the owner of Russo’s Market in Watertown, discovered this weekend after one of his employees delivered a series of unanticipated holiday performances inside the store that stopped customers dead in their tracks.

Russo said he was clueless to Guilherme Assuncao’s abilities until late Friday night, when the 23-year-old from Brazil offered to do a sound check on equipment to be used by classically-trained musicians over the weekend, as they entertained shoppers picking up groceries.

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