Sergio Casal Martínez (born 8 September 1962) is a former professional tennis player from Spain.

The pair were also the men's doubles runners-up at Wimbledon in 1987 and won the silver medal for Spain at the 1988 Olympics in Seoul.

Casal also won the US Open mixed doubles title in 1986, partnering Raffaella Reggi.

[citation needed] Casal won one top-level singles title at Florence in 1985.

He beat Boris Becker in a 1987 Davis Cup match.