Matías Fernández

Fernández began with the youth squads of Colo-Colo at the age of 12. His debut in the Primera División came on 1 August 2004 against Club Universidad de Chile, and a week later he scored his first two goals, against Cobresal.

Fernández would go on to net a total of eight goals in the 2004 Clausura, and was named best young player of the season. In the 2006 Apertura he helped his team capture their 24th title and, in December of the same year, he helped it reach the final of the Copa Sudamericana, lost to C.F. Pachuca of Mexico, by scoring nine times in six games for the tournament; he left Colo-Colo on a high note, winning the 2006 Clausura tournament and the South American Footballer of the Year award.

In late October 2006, Fernández was signed by Spanish club Villarreal CF for a fee of €8.7 million, joining compatriot Manuel Pellegrini who was the coach. The transaction was made before he received the "South American Player of the Year" award and, despite reports that Real Madrid and Chelsea were also interested, he agreed to terms and arrived at the Valencia airport on 27 December; on 7 January 2007 he made his La Liga debut in a 0–1 home loss against Valencia CF, scoring his first competitive goal three months later in a 3–0 league win at Gimnàstic de Tarragona.

Despite having had a buyout clause of €50 million inserted in his contract, Fernández failed to achieve significant playing time during his first three seasons, but still contributed with 30 matches and three goals in 2007–08 as the team finished a best-ever runners-up. On 10 May 2009, he scored from a penalty kick in a 3–3 away draw against eventual champions FC Barcelona.

On 1 July 2009, after being deemed surplus to requirements by new Villarreal coach Ernesto Valverde, Fernández moved to Sporting CP on a four-year contract, for €3.65 million, with a further €500,000 payable depending on appearances. Villarreal would retain 20% of the profit on any future sale of the player.

Fernández scored his first goal for his new team on 27 October 2009, in a 1–1 draw at Vitória de Guimarães, adding another the following week also in the Portuguese Primeira Liga, at home against C.S. Marítimo (again 1–1); in the UEFA Europa League he netted another goal, in injury time of the Lions' 3–0 win over Everton in the competition's round-of-16 (4–2 on aggregate).

Also a former under-17 international, Fernández quickly established as an integral part of the full side, netting five goals and appearing for the nation at the 2007 Copa América. After figuring prominently in the 2010 FIFA World Cup qualification campaign, he was selected for the finals in South Africa, playing – and starting – in the group stage against Honduras and Switzerland (both 1–0 wins), in an eventual last-16 exit.

On 27 July 2012, Fernández transferred to Italian club ACF Fiorentina for about €3.1 million, plus €1.5 million bonuses. During his spell at the Stadio Artemio Franchi, he was consistently bothered by physical problems.

Fernández married his Chilean wife in March 2013, but the couple's first child had already been born in late 2008. He was fined for speeding when he was driving from Santiago to Viña del Mar, to witness the baby's birth.

In May 2014, Fernández underwent an ankle surgery on his right foot, thus being unable to participate in that year's World Cup. He was included in the Chilean squad for the 2015 Copa América, being sent off in the opening match, a 2–0 win over Ecuador at the Estadio Nacional in Santiago; after having come as a 75th-minute substitute for Jorge Valdivia, he was one of four players on target in the final against Argentina, which ended 4–1 in a penalty shootout.

On 31 August 2016, Fernández moved to fellow Serie A team A.C. Milan on a season-long loan deal with an option to buy. He made his debut on 6 November, coming off the bench in the 2–1 away victory against U.S. Città di Palermo.

On 4 September 2017, free agent Fernández signed with Club Necaxa. On 4 February 2019 he joined Categoría Primera A defending champions Atlético Junior on a one-year contract, scoring a late equaliser on his debut 12 days later after coming on as a second-half substitute in the 1–1 home draw against Rionegro Águilas; he was named player of the match.

On 18 December 2019, Fernández returned to Colo-Colo by agreeing to a one-year contract with the option for a further season.