|Full name||Gustavo Lionel Siviero|
|Date of birth||13 September 1969|
|Place of birth||Laguna Paiva, Argentina|
|Height||1.82 m (6 ft 0 in)|
|Playing position||Centre back|
|1988–1991||Colón Santa Fe||106||(4)|
|1994–1996||Newell's Old Boys||82||(3)|
|2005||Colón Santa Fe||15||(0)|
|* Senior club appearances and goals counted for the domestic league only|
Born in Laguna Paiva, Santa Fe Province, Siviero began playing professionally Club Atlético Colón, moving in 1991 to Colombia with América de Cali. After only one season, he returned to his country and joined San Lorenzo de Almagro.
Siviero then played two seasons apiece with Newell's Old Boys and Club Atlético Lanús, always in the Primera División. In summer 1998, he signed with La Liga club RCD Mallorca alongside Lanús teammate Ariel Ibagaza (another Argentine, goalkeeper Carlos Roa, had done the same move the previous season). In his first year, acting as replacement for Real Madrid-bound Iván Campo, he was an undisputed starter as the Balearic Islands side narrowly missed on UEFA Champions League group stage entry; his official debut came in the first leg of the domestic Supercup, a 2–1 win at FC Barcelona (eventual 2–2 aggregate win).
In July 2002, aged 33, Siviero moved to Albacete Balompié also in Spain, reuniting with Roa, with the pair being instrumental as the Castile-La Mancha team returned to the top division in their debut season after a seven-year absence. After only six games in his last two years combined – with relegation befalling in 2005 – he returned to his first professional club Colón, retiring shortly after.
- Ibagaza y Siviero ya son bermellones (Ibagaza and Siviero are already vermilions); Mundo Deportivo, 28 June 1998 (in Spanish)
- Gustavo Siviero: “Nunca olvidaré mi estreno con el mallorca” (Gustavo Siviero: “I will never forget my Mallorca debut”); RCDM, 26 February 2009 (in Spanish)
- Siviero firma por una temporada (Siviero signs for one season); Mundo Deportivo, 24 July 2002 (in Spanish)
- Siviero deja el Albacete y se va al Colón de Santa Fe (Siviero leaves Albacete and goes to Colón de Santa Fe); Mundo Deportivo, 9 February 2005 (in Spanish)
- El técnico Goran Milojevic, cesado, y hoy el Baleares presentará a Siviero (Coach Goran Milojevic, sacked, and Baleares will present Siviero today); Mundo Deportivo, 4 October 2010 (in Spanish)