|Full name||Sergio Cidoncha Fernández|
|Date of birth||27 August 1990|
|Place of birth||El Escorial, Spain|
|Height||1.82 m (6 ft 0 in)|
|Playing position||Attacking midfielder|
|2009–2011||Atlético Madrid C||58||(13)|
|2011–2013||Atlético Madrid B||57||(7)|
|2013–2014||→ Zaragoza (loan)||29||(2)|
|* Senior club appearances and goals counted for the domestic league only and correct as of 14 May 2017.
Born in El Escorial, Madrid, Cidoncha was a product of local Atlético Madrid's youth ranks. He made his senior debuts in the 2009–10 season with the C-team, in the fourth division. Two seasons later, he was promoted to the reserves in the third level.
- Cidoncha llega al Zaragoza cedido por el Atlético de Madrid (Cidoncha arrives at Zaragoza on loan from Atlético de Madrid); Diario AS, 25 July 2013 (in Spanish)
- El Zaragoza recuerda lo difícil que es la Segunda (Zaragoza remembers just how difficult Segunda is); Marca, 17 August 2013 (in Spanish)
- Cidoncha, sexto fichaje del Albacete (Cidoncha, sixth signing of Albacete); Marca, 4 August 2014 (in Spanish)