|Full name||Diego Mateo Alustiza|
|Date of birth||7 August 1978|
|Place of birth||Roldán, Argentina|
|Height||1.78 m (5 ft 10 in)|
|Playing position||Defensive midfielder|
|Newell's Old Boys|
|1996–2000||Newell's Old Boys||92||(4)|
|2009–||Newell's Old Boys||144||(3)|
|* Senior club appearances and goals counted for the domestic league only and correct as of 8 November 2015.
Born in Roldán, Santa Fe, Mateo started his professional career in 1996 with Newell's Old Boys, where he made over 100 overall appearances, scoring four goals in the top division. In 2000 he joined U.S. Lecce in Italy, but left the club after appearing in only one fourth of the Serie A games during the season, with the Apulia side narrowly avoiding relegation.
In 2001 Mateo moved to Spain, where he would spend a great portion of his career: first, he was instrumental in helping Racing de Santander return to La Liga by scoring four times in 32 matches, and was relatively used in the following two top flight campaigns. In January 2005 he returned to the second division, playing for Real Valladolid.
Mateo returned to Argentina for a spell at San Lorenzo de Almagro, then went again to Spain and its second level after signing with Hércules CF. He then played two years in his country with Gimnasia y Esgrima de Jujuy but, after the team's relegation in 2009, the 31-year-old returned to his first club Newell's.
- Newell's Old Boys