The annual festival features hundreds of concerts held in venues of all sizes across the city, and staff at Copenhagen's oldest jazz club, La Fontaine, found themselves host to Gaga and her backing band, the Brian Newman Quintet, shortly after the singer completed her set with Tony Bennett at the Tivoli Gardens open air stage.

During her short visit, the Poker Face hitmaker thrilled audience members by belting out Piaf's signature song, which she has previously covered as part of her ongoing Cheek to Cheek tour with Bennett.

Gaga is making a habit of staging impromptu performances while on the road - last month (Jun15), the star sang at a new cocktail bar in New York City after completing her show with Bennett at the iconic Radio City Music Hall, while she pulled a similar stunt in London after one of their joint gigs was cancelled when the veteran crooner fell ill.