Constantin Frantzen
Constantin Frantzen is a German tennis player who specializes in doubles.
Frantzen has a career high ATP doubles ranking of world No. 42, achieved on 9 June 2025.
He played college tennis at Baylor University.
Career
2023–2024: ATP and Grand Slam 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, partnering Robin Haase.Doubles performance timeline
''Current through the 2026 Australian Open.''ATP Tour finals
Doubles: 4 (1 title, 3 runner-ups)
| Result | W–L | Date | Tournament | Tier | Surface | Partner | Opponents | Score | ||||||||||||||||||||||||||
| Loss | 0–1 | 2023 Moselle Open – Doubles| | Moselle Open, France | ATP 250 | Hard |  ATP Challenger finalsDoubles: 17 (8 titles, 9 runner-ups)
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