Sergio Daniel Martínez Alzuri (born 15 February 1969), nicknamed "Manteca", is a Uruguayan former professional footballer who played as a striker.

In his five years with Boca, Martínez won the Apertura in 1992 and the Copa de Oro in 1993, being crowned the Apertura 1993's top scorer with 12 goals and the Clausura 1997's with 15; upon his departure, he ranked seventh in the club's all-time scoring list with 86 goals in 167 games (all competitions).

In January 1998, Martínez moved to Spain to play for Deportivo de La Coruña,[1] only appearing in three La Liga matches in more than one year[2] before returning to his homeland to finish his career, at Club Nacional de Football.

In 1995, Martínez helped Uruguay win the Copa América, scoring the decisive penalty in the shootout against Brazil in the final.

[3] The recipient of 35 full caps,[4] he was also summoned for the 1990 FIFA World Cup, appearing in one game as the national side exited in the round of 16 (90 minutes against South Korea, 1–0 triumph).