Martín Gastón Demichelis (Spanish pronunciation: [maɾˈtin demiˈtʃelis]; born 20 December 1980) is an Argentine football manager and former player who is the head coach of Bundesliga club RB Leipzig.
A centre-back who could also operate as a defensive midfielder, Demichelis started his career in Argentina with River Plate. He spent most of his professional career with Bayern Munich in Germany (seven and a half years), winning 11 major titles with the team, including the Bundesliga four times. He also played in Spain with Espanyol, Atletico Madrid, and Málaga and in England with Manchester City, where he won the Premier League once and the League Cup twice. He made his debut for the Argentina national team in 2005, earning 51 caps. He represented the country at the 2010 and 2014 Word Cups, finishing runners-up at the latter. He also represented them at the 2005 Confederations Cup and the 2015 Copa América, with Argentina finishing runners-up at both tournaments.
Demichelis began his coaching career as an assistant at Málaga before coaching the under-19 and reserve teams of Bayern Munich. In 2022, he became manager of River Plate, winning the 2023 Argentine Primera División in his first season. He then had spells with Monterrey in Mexico, and Mallorca in Spain, before becoming head coach of RB Leipzig in 2026.
Born in Justiniano Posse, Córdoba, Demichelis started playing professionally in 2001, with Buenos Aires-based River Plate, having arrived at the club's youth system three years earlier.
He made his first-team – and first division – debut on 2 September 2001 in a game against Estudiantes, scoring his only goal for the team against Rosario Central.
On 28 April 2002, River Plate goalkeeper Ángel Comizzo was sent off with a minute of regulation time remaining against Racing Club, leaving Demichelis to take over in goal. He faced a direct free kick that hit the wall and was countered for the only goal of the game by Nelson Cuevas, as River won the Clausura title.
Demichelis signed for Bayern Munich in the 2003 summer, for €4.5 million. His first season in the Bundesliga was not very positive as he suffered a number of minor injuries, appearing in only 14 league games (21 in total) as the Bavarians finished in second position; in early 2004 he appeared in his only game with the reserves, against Stuttgarter Kickers.
Under new coach Felix Magath, Demichelis became a regular starter for Bayern, appearing in 75 official matches in two seasons combined as the team won back-to-back doubles, achieving a total of four during his spell.
Returning Bayern boss Ottmar Hitzfeld successfully reconverted Demichelis from a defensive midfielder into a central defender. In 2008–09 he netted a career-best four goals in 29 games, but the title was lost to VfL Wolfsburg. However, the player often clashed with the new manager Louis van Gaal, starting immediately after the first matchday after being dropped from the starting XI for the 2010–11 opener against Wolfsburg, with Demichelis requesting that van Gaal omit him from the squad altogether, which the coach did; the player thereafter voiced to the press that it would be probable that he and the club went separate ways.
On 29 October 2010, benefitting from a run of injuries in the squad, Demichelis made one of his last appearances for Bayern, heading a goal in a 4–2 home win against SC Freiburg.
In late December 2010, Demichelis agreed to a deal with Spanish club Málaga, initially until the end of the 2010–11 season, with the latter retaining the option to extend the contract for a further two seasons. He rejoined former River Plate manager Manuel Pellegrini, and made his La Liga debut on 8 January 2011, scoring in a 1–1 home draw against Athletic Bilbao.
During his first four months with Málaga, Demichelis was sent off twice, but also started in all the matches he was available, being essential – as another January 2011 signee, Júlio Baptista – as the club eventually avoided relegation. On 22 August 2012, he scored the club's first-ever UEFA Champions League goal, netting the opener in the 2–0 playoff home win against Panathinaikos (also the aggregate score).
On 11 July 2013, Demichelis signed for Atlético Madrid on a one-year contract, after his deal with Málaga expired. In December, he started legal action against the latter over "non-payments", relating to "€400,000 of unpaid wages as well as bonuses".
On 1 September 2013, Demichelis joined former Málaga boss Pellegrini and signed with Manchester City, penning a two-year contract for a reported £4.2 million. He had been with Atlético for less than two months, and had yet to make an appearance.
Demichelis made his first appearance for his new club on 27 October 2013, starting in a 1–2 Premier League loss at Chelsea after recovering from a knee injury. On 18 February of the following year, he was sent off against Barcelona in the club's Champions League round-of-16 0–2 home defeat, after fouling Lionel Messi and giving away a penalty.
Despite Demichelis's rocky start at City, Pellegrini kept faith in him. On 15 March 2014, after club captain Vincent Kompany was sent off, he was instrumental in a 2–0 victory over Hull City. The following weekend he scored his first goal, contributing to a 5–0 home win over Fulham; his good run of form in the last two months of the season helped his team win the league title, and also helped him rejoin the national side.
On 12 March 2015, Demichelis renewed his expiring contract until June of the following year. A year later, he was charged by The Football Association for 12 breaches of their rules against gambling on matches, and accepted the charge; he was fined £22,058 for the breach.
On 10 June 2016, Demichelis was released.