Constantin Frantzen

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

Current through the 2026 Winston-Salem Open.

Significant finals

ATP 1000 tournaments

Doubles: 1 (runner-up)

ATP Tour finals

Doubles: 7 (1 title, 6 runner-ups) LegendGrand Slam (–)ATP 1000 (0–1)ATP 500 (0–1)ATP 250 (1–4)Finals by surfaceHard (1–4)Clay (0–2)Grass (–)Finals by settingOutdoor (1–3)Indoor (0–2)

ATP Challenger finals

Doubles: 18 (9 titles, 9 runner-ups) Finals by surfaceHard (2–5)Clay (7–3)Carpet (0–1)

ITF Tour finals

Doubles: 11 (5 titles, 6 runner-ups) Finals by surfaceHard (1–4)Clay (3–2)Carpet (1–0)