Constantin Frantzen (born 16 March 1998) is a German professional tennis player who specializes in doubles. He has a career-high ATP doubles ranking of world No. 29 achieved on 24 August 2026.

Frantzen has won one ATP Tour doubles title at the 2025 Chengdu Open, with Robin Haase.

He played college tennis at Baylor University.

Career

2023–2024: ATP and major debuts in doubles

Frantzen made his ATP Tour doubles main draw debut at the Swiss Open Gstaad alongside Hendrik Jebens.

He reached his first ATP Tour final at the Moselle Open with partner Jebens, but lost to Hugo Nys and Jan Zieliński. Frantzen reached his second ATP Tour final at the 2024 Generali Open Kitzbühel also alongside Jebens but lost to Alexander Erler and Andreas Mies. The pair also made it to the 2024 Hangzhou Open final, losing to Jeevan Nedunchezhiyan and Vijay Sundar Prashanth in the final.

2025: Maiden ATP title

In September, Frantzen won his first doubles title on the ATP Tour at the Chengdu Open, playing alongside Robin Haase.

Doubles performance timeline

Key
WFSFQF#RRRQ#DNQANH

Current through the 2026 Winston-Salem Open.

Tournament2023202420252026SRW–L
Grand Slam tournaments
Australian OpenA1R1R1R0 / 30–3
French OpenA1R2R1R0 / 31–3
WimbledonAQF3R1R0 / 35–3
US OpenA1RQF0 / 23–2
Win–loss0–03–46–40–30 / 119–11
ATP 1000 tournaments
Indian Wells OpenAA1RQF0 / 22–2
Miami OpenAA1R1R0 / 20–2
Madrid OpenAA2RA0 / 11–1
Cincinnati OpenAAAF0 / 14–1
Win–loss0–00–01–36–30 / 67–6
Career statistics
Tournaments520252171
Titles00101
Finals12137
Overall win–loss3–519–2023–2324–2169–69
Year-end ranking65524850%

Significant finals

ATP 1000 tournaments

Doubles: 1 (runner-up)

ResultYearTournamentSurfacePartnerOpponentsScore
Loss2026Cincinnati OpenHardNetherlands Robin HaaseBrazil Orlando Luz Brazil Rafael Matos4–6, 6–3, [7–10]

ATP Tour finals

Doubles: 7 (1 title, 6 runner-ups)

Legend
Legend Grand Slam (–) ATP 1000 (0–1) ATP 500 (0–1) ATP 250 (1–4)Finals by surface Hard (1–4) Clay (0–2) Grass (–)Finals by setting Outdoor (1–3) Indoor (0–2)
Grand Slam (–)
ATP 1000 (0–1)
ATP 500 (0–1)
ATP 250 (1–4)
Finals by surface
Hard (1–4)
Clay (0–2)
Grass (–)
Finals by setting
Outdoor (1–3)
Indoor (0–2)
ResultW–LDateTournamentTierSurfacePartnerOpponentsScore
Loss0–1Nov 2023Moselle Open, FranceATP 250Hard (i)Germany Hendrik JebensMonaco Hugo Nys Poland Jan Zieliński4–6, 4–6
Loss0–2Jul 2024Austrian Open, AustriaATP 250ClayGermany Hendrik JebensAustria Alexander Erler Germany Andreas Mies3–6, 6–3, [6–10]
Loss0–3Sep 2024Hangzhou Open, ChinaATP 250HardGermany Hendrik JebensIndia Jeevan Nedunchezhiyan India Vijay Sundar Prashanth6–4, 6–7(5–7), [7–10]
Win1–3Sep 2025Chengdu Open, ChinaATP 250HardNetherlands Robin HaaseUnited States Vasil Kirkov Netherlands Bart Stevens4–6, 6–3, [10–7]
Loss1–4Feb 2026Open Occitanie, FranceATP 250Hard (i)Netherlands Robin HaaseFrance Théo Arribagé France Albano Olivetti6–7(6–8), 1–6
Loss1–5Feb 2026Rio Open, BrazilATP 500ClayNetherlands Robin HaaseBrazil João Fonseca Brazil Marcelo Melo6–4, 3–6, [8–10]
Loss1–6Aug 2026Cincinnati Open, United StatesATP 1000HardNetherlands Robin HaaseBrazil Orlando Luz Brazil Rafael Matos4–6, 6–3, [7–10]

ATP Challenger finals

Doubles: 18 (9 titles, 9 runner-ups)

Finals by surface
Hard (2–5)
Clay (7–3)
Carpet (0–1)
ResultW–LDateTournamentSurfacePartnerOpponentsScore
Loss0–1Sep 2022Columbus, United StatesHardUnited Kingdom Charles BroomUnited Kingdom Julian Cash United Kingdom Henry Patten2–6, 5–7
Loss0–2Oct 2022Las Vegas, United StatesHardUnited States Reese StalderUnited Kingdom Julian Cash United Kingdom Henry Patten4–6, 6–7(1–7)
Loss0–3Mar 2023Pau, FranceHard (i)United Kingdom Julian CashFrance Dan Added France Albano Olivetti6–3, 1–6, [8–10]
Loss0–4Mar 2023Lugano, SwitzerlandHard (i)Germany Hendrik JebensBelgium Zizou Bergs Netherlands David Pel2–6, 6–7(6–8)
Win1–4Mar 2023Biel/Bienne, SwitzerlandHard (i)Germany Hendrik JebensRomania Victor Vlad Cornea Croatia Franko Škugor6–2, 6–4
Loss1–5May 2023Mauthausen, AustriaClayGermany Hendrik JebensMonaco Romain Arneodo Austria Sam Weissborn4–6, 2–6
Win2–5Jun 2023Heilbronn, GermanyClayGermany Hendrik JebensRomania Victor Vlad Cornea Austria Philipp Oswald7–6(9–7), 6–4
Loss2–6Jun 2023Lyon, FranceClayGermany Hendrik JebensFrance Manuel Guinard France Grégoire Jacq4–6, 6–2, [7–10]
Win3–6Aug 2023Augsburg, GermanyClayGermany Hendrik JebensFrance Constantin Kouzmine Ukraine Volodymyr Uzhylovskyi6–2, 6–2
Win4–6Sep 2023Como, ItalyClayGermany Hendrik JebensSweden Filip Bergevi Netherlands Mick Veldheer6–3, 6–4
Win5–6Sep 2023Bad Waltersdorf, AustriaClayGermany Hendrik JebensItaly Marco Bortolotti Italy Francesco Passaro6–1, 6–2
Win6–6Oct 2023Orléans, FranceHard (i)Germany Hendrik JebensUnited Kingdom Henry Patten Australia John-Patrick Smith7–6(7–5), 7–6(14–12)
Loss6–7Nov 2023Ismaning, GermanyCarpet (i)Germany Hendrik JebensIndia Sriram Balaji Germany Andre Begemann6–7(4–7), 4–6
Loss6–8Mar 2024Lugano, SwitzerlandHard (i)Germany Hendrik JebensNetherlands Sander Arends Netherlands Sem Verbeek7–6(11–9), 6–7(1–7), [8–10]
Win7–8May 2024Mauthausen, AustriaClayGermany Hendrik JebensUnited States Ryan Seggerman United States Patrik Trhac6–4, 6–4
Win8–8Mar 2025Naples, ItalyClayAustria Alexander ErlerFrance Geoffrey Blancaneaux France Albano Olivetti6–4, 6–4
Loss8–9Jun 2025Sassuolo, ItalyClayAustria Alexander ErlerAustralia Matthew Romios United States Ryan Seggerman6–7(4–7), 6–3, [7–10]
Win9–9May 2026Valencia, SpainClayNetherlands Robin HaaseNetherlands Sander Arends Netherlands David Pel6–4, 6–7(5–7), [11–9]

ITF Tour finals

Doubles: 11 (5 titles, 6 runner-ups)

Finals by surface
Hard (1–4)
Clay (3–2)
Carpet (1–0)
ResultW–LDateTournamentSurfacePartnerOpponentsScore
Win1–0Oct 2015Ismaning, GermanyCarpet (i)Austria Alexander ErlerGermany Kevin Krawietz Germany Tim Sandkaulen2–6, 7–5(7–5), [10–8]
Loss1–1Oct 2021M15 Lubbock, United StatesHardSlovenia Sven LahUnited States Sekou Bangoura Netherlands Gijs Brouwer4–6, 6–4, [5–10]
Loss1–2Nov 2021M25 Harlingen, United StatesHardRomania Gabi Adrian BoitanPhilippines Francis Alcantara United Kingdom Mark Whitehouse6–7(3–7), 7–5, [7–10]
Loss1–3Feb 2022M25 Glasgow, United KingdomHard (i)United Kingdom Charles BroomNetherlands Gijs Brouwer United Kingdom Aidan McHugh6–4, 6–7(1–7), [4–10]
Loss1–4Apr 2022M15 Monastir, TunisiaHardGermany Tim SandkaulenPoland Szymon Kielan Poland Michał Mikuła6–7(4–7), 7–6(7–2), [2–10]
Win2–4Apr 2022M15 Monastir, TunisiaHardUnited Kingdom Charles BroomChina Li Zhe China Bu Yunchaokete7–5, 2–6, [10–8]
Win3–4May 2022M15 Meerbusch, GermanyClayGermany Tim SandkaulenChile Miguel Fernando Pereira Brazil Gabriel Roveri Sidney7–6(7–5), 6–4
Win4–4May 2022M25 Most, Czech RepublicClayGermany Tim SandkaulenCzech Republic Marek Gengel Czech Republic David Poljak6–3, 4–6, [10–7]
Loss4–5Jun 2022M25 Arlon, BelgiumClayGermany Tim SandkaulenIndia Anirudh Chandrasekar India Vijay Sundar Prashanth6–7(5–7), 4–6
Win5–5Jul 2022M25 Kassel, GermanyClayGermany Tim SandkaulenGermany Tom Gentzsch Germany Leopold Zima6–4, 6–2
Loss5–6Aug 2022M25 Wetzlar, GermanyClayGermany Tim SandkaulenLebanon Benjamin Hassan France Tristan Lamasine4–6, 3–6

External links