2017–2019: Grand Slam debut Müller made his ATP main draw debut at the
2017 French Open after receiving a wildcard to the singles main draw. He was defeated by
Thiago Monteiro in the first round. He qualified for the
2019 French Open but lost in the first round to
Roberto Carballés Baena.
2021: First Grand Slam win, top 200 debut At the
2021 Australian Open Müller won his first Grand Slam match as a lucky loser defeating
Juan Ignacio Londero. As a result, he entered the top 200 at a career-high of World No. 194 on 22 February 2021.
2022: First Challenger title, top 150 debut In June, Müller won his first Challenger tournament in
Blois, France, defeating
Nikola Milojević. A month later, he made his top 150 debut on 25 July 2022 at world No. 149.
2023: First ATP final, top 100 and Masters debuts At the
2023 Qatar ExxonMobil Open in Doha, Müller as a qualifier reached his first ATP quarterfinal in his career, defeating
Nikoloz Basilashvili and eighth seed
Botic van de Zandschulp. He lost to
Andy Murray. At the
2023 Grand Prix Hassan II he reached a second quarterfinal defeating sixth seed
Richard Gasquet and
Francesco Passaro. Next he defeated top seed
Lorenzo Musetti to reach his first ATP semifinal in a close to two hours match. He then faced Russian
Pavel Kotov, defeating him also in two hours in straight sets to reach his first ATP final, before losing to
Roberto Carballés Baena. As a result he secured a new career high singles ranking into the top 100 at world No. 96 on 10 April 2023. He made his Masters debut at the
2023 Italian Open as a qualifier and recorded his first win defeating
Kyle Edmund. Müller reached a new career-high ranking of No. 82 on 26 June 2023, following his first title at a Challenger 125 level at the
2023 Emilia-Romagna Open in
Montechiarugolo, Italy, defeating
Francesco Maestrelli. He made his debut at
Wimbledon, defeating compatriot
Arthur Rinderknech in the first round for his second win in a Major. He then lost to top seed
Carlos Alcaraz. At the
US Open, Müller faced second seed
Novak Djokovic in the first round, losing in straight sets. He received a wildcard for the main draw of the
2023 Rolex Paris Masters.
2024: First top 10 win, Masters fourth round In January, following a quarterfinal showing as a qualifier at the
2024 ASB Classic where he defeated compatriot
Benjamin Bonzi and third seed
Francisco Cerúndolo, Müller reached the top 75 in the rankings on 15 January 2024. In February, Muller lost to
Andy Murray in the first round of the
ATP Qatar Open. This was Andy Murray's first victory since October 2023. In May, Müller reached the fourth round of a
Masters at the
Italian Open for the first time in his career by defeating
Márton Fucsovics, compatriot and 31st seed
Arthur Fils, and fourth seed
Andrey Rublev, having reached the main draw as a qualifier. The win against Rublev ended the Madrid champion seven-match winning streak and was his first career win against a top 10 player. As a result he made it back to the top 100 climbing close to 20 positions up in the rankings. He lost to
Nicolás Jarry in the fourth round. In June, Müller reached his first
Challenger final in a year in
Lyon, losing to top seed
Hugo Gaston in the final. In July, he won his first
Challenger title in more than a year in
San Marino, defeating
Tseng Chun-hsin in the final. Müller received a wildcard for the main draw of the
US Open, where he reached the second round, recording his first win at the tournament over
Adam Walton. He lost to fourth seed
Alexander Zverev. In October, Müller reached the third round at a
Masters for the second time in his career at the
Shanghai Masters, defeating
Luca Nardi in the first round and eighteenth seed
Félix Auger-Aliassime in the second round before losing to tenth seed
Stefanos Tsitsipas in the third round.
2025: Maiden ATP title, ATP 500 final, top 40 In January, Müller won his maiden ATP title at the
Hong Kong Open defeating
Kei Nishikori in the final. In February, Müller reached his first
ATP 500 final at the
Rio Open defeating
João Fonseca and three Argentine players, with upsets of eighth seed
Tomás Martín Etcheverry and fourth seed
Francisco Cerúndolo, and
Francisco Comesana, and setting his record to 15-1 in his past 16 encounters against Argentines across all levels (10-0 on clay). As a result he entered the Top 50 on 24 February 2024. Next he setup a meeting in the final with defending champion
Sebastián Báez, after becoming the first Frenchman to reach the Rio title round, which he lost in straight sets. Ranked No. 41, Müller lost for a second time to Novak Djokovic in the first round at
Wimbledon. ==Performance timeline==