Baccara is a female vocal duo formed in 1977 by Spanish artists Mayte Mateos ( born 7 February 1951 in Logroño ) and María Mendiola ( born 4 April 1952 in Madrid ) . The pair rapidly achieved international success with their debut single " Yes Sir , I Can Boogie " , which reached number one across much of Europe and became the best-selling single of all-time by a female group , eventually selling more than 18 million copies worldwide . A successful follow-up single ( " Sorry , I 'm a Lady " ) and European tour led to a number of album releases , numerous television appearances and the duo 's selection to represent Luxembourg in the '' Eurovision Song Contest 1978 ''
Eurovision Song Contest 1978
Eurovision Song Contest 1978
Baccara