Gilles Müller (Luxembourgish pronunciation: [ˈʒil ˈmylɐ]; born 9 May 1983) is a Luxembourgish former professional tennis player. He is a two-time major singles quarterfinalist, making him by far the most successful male tennis player in Luxembourgish history. Müller won two titles on the ATP Tour and achieved a career-high ATP singles ranking of world No. 21 on 31 July 2017. He was known for his powerful left-handed serve and net skills. Following his retirement, Müller was appointed as Luxembourg's Davis Cup team captain.
Müller played his first junior match in 1997 at the age of 14 at a grade 4 tournament in Luxembourg. 2001 was Müller's most successful year in juniors. He started off by making the semifinals of the Junior Australian Open where he lost to the No. 1 ranked junior Janko Tipsarević of Yugoslavia (1–6, 6–4, 2–6). Following an early exit at the Junior French Open, He reached the final of the Boys' Singles at the 2001 Wimbledon Championships, where he was defeated by Roman Valent of Switzerland (6–3, 5–7, 3–6). He won the Boys' Singles final at the 2001 US Open, defeating Taiwan's Yeu-Tzuoo Wang (7–6, 6–2). He attained No. 1 ranking on the junior circuit on September 10, 2001, and finished the year with the ranking. He ended his junior career after an early exit at the Orange Bowl with an overall singles record of 81–29 throughout his junior career.
Junior Grand Slam results – Singles:
Although beginning to play ITF events in 2000, Müller did not turn pro until 2001 at the age of 18. Between April 2001 and August 2002, He won a total of four ITF futures events. He made his ATP debut at the 2002 Rosmalen Grass Court Championships after receiving a wildcard into the singles main draw where he lost in the first round to Ivo Heuberger (2–6, 6–3, 6–7(8–10)).
By the time 2003 came, Müller had already broke into the top 300 and started consistently playing in ATP Challenger Tour events where he made his first challenger final in April and won his first challenger title in July. He qualified for his second ATP event, the 2003 Copenhagen Open where he lost in the first round to Jean-René Lisnard (5–7, 4–6).
Müller entered the qualifying draws of the 2003 French Open and the 2003 US Open, losing both in the first round.
2004–2005: ATP Tour finals and wins against top-10 players
Müller began 2004 with his first ATP Tour match win at the 2004 Auckland Open where he defeated Nicolás Lapentti (7–5, 6–7(3–7), 6–1) and his first grand slam at the 2004 Australian Open where he lost in the first round to David Ferrer (6–7(4–7), 1–6, 3–6). His breakthrough event came at the 2004 Legg Mason Tennis Classic where he made his first ATP Tour final and defeated 1st seed and world No. 6 Andre Agassi (4–6, 5–7) to register his first win over a top-10 player. He lost in the final to 2nd seed and world No. 8 Lleyton Hewitt (3–6, 4–6). His result at the tournament would push his ranking into the top-100 for the first time in his career. He also defeated world No. 10 David Nalbandian (7–6(7–4), 3–6, 4–6,) at the 2004 Japan Open for his second win over a top-10 player. He finished 2004 his a year-end ranking of 69.
At the 2005 Wimbledon Championships, Müller stunned 4th seed and world No. 3 Rafael Nadal (6–4, 4–6, 6–3, 6–4) in the second round. He lost in the third round to 27th seed Richard Gasquet (6–7(3–7), 3–6, 3–6). He made his second ATP Tour final at the 2005 Los Angeles Open where he lost to top seed and world No. 6 Andre Agassi (4–6, 5–7). At the 2005 US Open, he stunned 4th seed and world No. 3 Andy Roddick (6–7(4–7), 6–7(8–10), 6–7(1–7)). He lost in the second round to eventual semifinalist Robby Ginepri (1–6, 1–6, 4–6). He finished 2005 with a year-end ranking of 76.
2006–2007: Back outside of the top 100
Müller's success started to die down in 2006. He started to get worse results in ATP events which dropped his ranking back outside of the top-100 to 105 by the end of the year. After January 2007, he returned to solely playing challenger events and had to start qualifying for grand slams and ATP events despite usually gaining automatic entry since 2005.
2008: First Grand Slam quarterfinal
At the 2008 US Open, Müller, ranked 130 at the time, had to go through the qualification tournament. He reached the main draw and advanced to the quarterfinals of a Grand Slam tournament for the first time in his career, earnining a win over fifth-seeded Nikolay Davydenko in the fourth round. He lost to defending and eventual champion Roger Federer in straight sets (6–7, 4–6, 6–7).
2009–2013: Struggles with injuries
On 19 January 2009, Müller beat Spaniard Feliciano López (6–3, 7–6, 4–6, 4–6, 16–14) in an epic four-hour, 24-minute match in the first round of the 2009 Australian Open. His run in the tournament ended in the third round by the eighth-seeded Juan Martín del Potro.
In September 2011, he advanced to the fourth round of the US Open, losing to Rafael Nadal, whom he had already lost to in the third round of Wimbledon earlier that same year.
Müller registered his 100th singles win by defeating Australian Marinko Matosevic (7–6, 6–4) in Atlanta. He also reached his first ATP final in seven years at the 2012 Atlanta Open final, losing to Andy Roddick (6–1, 6–7, 2–6) after the American came back from one set and one break down to win what would be Roddick's last final on the ATP Tour.
Müller's final match in 2013 was at the 2013 French Open where he lost in round 1 to Roberto Bautista Agut. He finished the year at No. 368 in the world rankings after missing the second half of the season with an elbow injury.