Gauthier Onclin

Gauthier Onclin (born 26 February 2001) is a Belgian professional tennis player. He has a career-high ATP singles ranking of No. 158 achieved on 24 August 2026 and a doubles ranking of No. 827 achieved on 12 April 2021. Onclin plays mostly on the ATP Challenger Tour, where he has won two singles titles.

Career

2023: ATP debut in doubles In January, Onclin reached the semifinals of the 2023 BW Open in Ottignies-Louvain-la-Neuve where he lost to eventual champion and compatriot David Goffin.

In May, he defeated the higher-ranked Elias Ymer at a Challenger event in Bordeaux in the first round. At the 2023 French Open he defeated Nicholas David Ionel in straight sets in the first round of qualifying before losing to Argentine Thiago Agustin Tirante in three sets. Onclin got his revenge over the Argentine in the qualifying at the 2023 Wimbledon Championships, winning in straight sets during his first ever grass-court summer, as his junior years coincided with the grass-court portion of the Tour cancellation due to the COVID-19 pandemic.

In October, he received a wildcard in doubles for the European Open in Antwerp, alongside compatriot Michael Geerts. At the same tournament, in the qualifying singles competition, he defeated higher-ranked American Maxime Cressy.

2024: Maiden Challenger final In May, Onclin reached his first Challenger final at the Prague Open. He lost to the former world No. 35 Jiří Veselý. In October and November 2024 he reached two M25 finals in Portugal where he faced the same opponent, losing the first to Frederico Ferreira Silva but winning the second at the Vale do Lobo Open III. He closed out 2024 with a second title in two weeks, and 12th ITF title, winning the M25 in Monastir, Tunisia, recording 10 consecutive victories on the ITF circuit.

2025: Grand Slam and top 200 debuts Onclin started the season by increasing his 2024 winning streak to 13 matches after he made it through the qualifying rounds at the Australian Open into the main draw for his Grand Slam debut, defeating Roman Andres Burruchaga and Americans Aleksandar Kovacevic and Mackenzie McDonald. Despite winning the opening set, he lost to Reilly Opelka in the first round.

2026: First Challenger titles, first ATP win As top seed, Onclin won his first ATP Challenger title at the Ivory Coast Open, defeating Hamish Stewart in the final in two tiebreak sets. The following week, he claimed his second Challenger title by overcoming Michael Mmoh in the final of the Ivory Coast Open 2 in straight sets.

In June, ranked No. 186, Onclin earned his first ATP Tour win at the Stuttgart Open as a qualifier, by defeating Fábián Marozsán. He lost to Giovanni Mpetshi Perricard in the second round.

Performance timeline

Singles Current through the 2026 Australian Open.

ATP Challenger Tour finals

Singles: 3 (2 titles, 1 runner-up)

Finals by surfaceHard (2–0)Clay (0–1)