From 1988 until his death, he was the manager of a total of nine clubs in France and Persian Gulf region, the Guinea, Senegal, United Arab Emirates and Qatar national football teams.

He was perhaps most famous for coaching Senegal to the quarter-finals of the 2002 FIFA World Cup, including a surprise victory over defending champions France in the opening match of the tournament.

Metsu had his heyday at Valenciennes between 1975 and 1979, scoring his highest number of club goals, 14 (in 134 league - all of them Division 1 - and Coupe de France matches), while playing alongside top players such as Didier Six and Roger Milla.

He was sacked on 28 February 1993 after it had managed to win just 5 of its first 27 Division 1 matches in the current season, the board summoning him to a meeting and inquiring: "So have you heard the gossip?

He lasted a year there, then had spells at Sedan (1995–1998) and Valence (1998–1999) before, he applied successfully to become the manager of the Guinea national football team.

"At that time I felt like I had had too much of football but African players reinvigorated me," Metsu said in an interview with La Voix du Nord daily in 2011.

[4] Metsu immediately began fostering the esprit de corps that would fuel his Senegal side, recalling several players whom the Senegalese Football Federation did not want in the national team because of perceived indiscipline.

[3] Metsu's relaxed but inspiring coaching style quickly whipped his team into shape to the admiration of both fans and officials.

Although they lost to Cameroon 3–2 on penalties, the White Sorcerer, his sobriquet given by the local press, and his charges were given a red carpet reception when they arrived back home in Dakar.

In a passionate speech to his team before the opening match of the tournament (France versus Senegal), Metsu used the disparaging comments to stir his players.

Senegal pulled off a major surprise by beating the reigning world and European champions 1–0, with Pape Bouba Diop scoring the only goal.

[4][7] After Senegal had defeated France in the opening match of the 2002 World Cup finals, Senegalese president Abdoulaye Wade declared a national holiday.

Metsu's connection to the country had been sealed when he married a Muslim by the name of Rokhaya 'Daba' Ndiaye, one day after he had converted from Christianity to Islam in Senegal.

[8][9][10][11][12] Metsu was mostly described in Senegal as a coach who inculcated the culture of courage and relentlessness in the Lions of Teranga, which subsequently influenced the junior ranks and the nation's club sides.

[4] Metsu left his post as the manager of the Senegal national team in 2002, at the height of differences with the country's football officials.

[6] In 2005, Metsu coached his new club to the Qatar Stars League title in his first season, with a 14-point winning margin over the second-placed Al Rayyan SC.

[6] Metsu returned to the UAE as the national team's manager in 2006, coaching his side to victory in the 18th Arabian Gulf Cup in front of a packed stadium in Abu Dhabi on 30 January 2007.

Despite his contract lasting until 2010, Metsu resigned from his post on 22 September 2008 after the UAE suffered defeats in their first two matches of the 2010 World Cup qualification - AFC fourth round Group B.

In the latter tournament, Qatar finished second in their group with two wins and a defeat before it was beaten 3–2 by Japan in the quarter-finals on 21 January 2011, resulting in Metsu's sacking in February 2011.

He was appointed the manager of Al-Gharafa in March 2011 on a three-year contract, returning to the club that he had guided to win the Qatar Stars League in 2005.

Metsu was sacked from his post on 15 March 2012, just one year into his contract, due to poor results including a disheartening 5–1 home defeat to Al Rayyan that caused the team to drop to seventh place in the Qatar Stars League standings.

On 12 July 2012, Metsu was named as the new Al Wasl FC head coach, replacing Diego Maradona who had been sacked two days earlier.