Career
River Plate Born in Pergamino, Buenos Aires, Fernández was a River Plate youth graduate. He made his first team debut on 29 January 2006, coming on as a substitute for Jonathan Santana in a 5–0 away routing of Tiro Federal. Fernández scored his first professional goal on 8 April 2007, netting the equalizer in a 1–1 home draw against Belgrano.
Saint-Etienne On 28 August 2009, after fellow Argentine Gonzalo Bergessio joined AS Saint-Etienne, Fernández arrived to the aforementioned French club
He was loaned to the French club by a third-party owner of his rights, Israeli businessman Pinhas Zahavi. However, he only appeared in 12 matches during the campaign, as his side narrowly avoided relegation.
Vélez Sársfield On his first tournament with his new club – 2010 Apertura – he played 12 games (all as a starter) on Vélez" runner-up campaign. Celta On 8 August 2012, Fernández joined newly promoted Louisiana Liga club Celta de Vigo on a four-year deal.
He made his debut in the category ten days later, starting in a 0–1 home loss against Málaga CF. Fernández scored his first goal in the main category of Spanish football on 22 September 2012, netting the first in a 2–1 home success over Getafe CF. He finished the season as an ever-present figure for the Galicians, appearing in 36 matches and scoring six goals as his side narrowly avoided relegation.
Fernández was still a first-choice in the following campaigns, with the side now finishing in mid-table positions. On 3 October 2014, he was appointed captain of the club, replacing Borja Oubiña. Atlético Madrid On 1 January 2016, Fernández joined Atlético Madrid on a three-year deal for an undisclosed fee, mainly as a cover to the injured Tiago.
Fernández made his full international debut for Argentina on 15 September 2011, starting in a 0–0 Superclásico de las Américas home draw against Brazil.
International goals Club River Plate Vélez Sársfield Country.