# Constantin Frantzen

Constantin Frantzen (born 16 March 1998) is a German tennis player who specializes in doubles.
Frantzen has a career high ATP doubles ranking of world No. 45, achieved on 12 August 2024. He has won seven ATP Challenger doubles titles, all with partner Hendrik Jebens.
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.

## Doubles performance timeline

Key :
| W | F | SF | QF | #R | RR | Q# | DNQ | A | NH |
Current through the 2025 Indian Wells Open.
| Tournament | 2023 | 2024 | 2025 | SR | W–L |
| Grand Slam tournaments ||||||
| Australian Open | A | 1R | 1R | 0 / 2 | 0–2 |
| French Open | A | 1R | | 0 / 1 | 0–1 |
| Wimbledon | A | QF | | 0 / 1 | 3–1 |
| US Open | A | 1R | | 0 / 1 | 0–1 |
| Win–loss | 0–0 | 3–4 | 0–1 | 0 / 5 | 3–5 |
| ATP Masters 1000 ||||||
| Indian Wells Open | A | A | 1R | 0 / 1 | 0–1 |
| Miami Open | A | A | | 0 / 0 | 0–0 |
| Win–loss | 0–0 | 0–0 | 0–1 | 0 / 1 | 0–1 |
| Career statistics ||||||
| Tournaments | 5 | 20 | 9 | 34 | 34 |
| Titles | 0 | 0 | 0 | 0 | 0 |
| Finals | 1 | 2 | 0 | 3 | 3 |
| Overall win–loss | 3–5 | 19–20 | 5–8 | 27–33 | 27–33 |
| Year-end ranking | 65 | 52 | | 45% | 45% |

## ATP Tour finals
### Doubles: 3 (3 runner-ups)

* Legend
* Grand Slam tournaments (0–0)
* ATP Masters 1000 (0–0)
* ATP 500 (0–0)
* ATP 250 (0–3)
* Finals by surface
* Hard (0–2)
* Clay (0–1)
* Grass (0–0)
| Result | W–L | Date | Tournament | Tier | Surface | Partner | Opponents | Score |
| Loss | 0–1 | Nov 2023 | Moselle Open, France | ATP 250 | Hard (i) | Hendrik Jebens | Hugo Nys Jan Zieliński | 4–6, 4–6 |
| Loss | 0–2 | Jul 2024 | Austrian Open Kitzbühel, Austria | ATP 250 | Clay | Hendrik Jebens | Alexander Erler Andreas Mies | 3–6, 6–3, [6–10] |
| Loss | 0–3 | Sep 2024 | Hangzhou Open, China | ATP 250 | Hard | Hendrik Jebens | Jeevan Nedunchezhiyan Vijay Sundar Prashanth | 6–4, 6–7$^{(5–7)}$, [7–10] |

## ATP Challenger finals
### Doubles: 15 (7–8)

* Finals by surface
* Hard (2–5)
* Clay (5–2)
* Carpet (0–1)
| Result | W–L | Date | Tournament | Surface | Partner | Opponents | Score |
| Loss | 0–1 | Sep 2022 | Columbus, United States | Hard | Charles Broom | Julian Cash Henry Patten | 2–6, 5–7 |
| Loss | 0–2 | Oct 2022 | Las Vegas, United States | Hard | Reese Stalder | Julian Cash Henry Patten | 4–6, 6–7$^{(1–7)}$ |
| Loss | 0–3 | Mar 2023 | Pau, France | Hard (i) | Julian Cash | Dan Added Albano Olivetti | 6–3, 1–6, [8–10] |
| Loss | 0–4 | Mar 2023 | Lugano, Switzerland | Hard (i) | Hendrik Jebens | Zizou Bergs David Pel | 2–6, 6–7$^{(6–8)}$ |
| Win | 1–4 | Mar 2023 | Biel/Bienne, Switzerland | Hard (i) | Hendrik Jebens | Victor Vlad Cornea Franko Škugor | 6–2, 6–4 |
| Loss | 1–5 | May 2023 | Mauthausen, Austria | Clay | Hendrik Jebens | Romain Arneodo Sam Weissborn | 4–6, 2–6 |
| Win | 2–5 | Jun 2023 | Heilbronn, Germany | Clay | Hendrik Jebens | Victor Vlad Cornea Philipp Oswald | 7–6$^{(9–7)}$, 6–4 |
| Loss | 2–6 | Jun 2023 | Lyon, France | Clay | Hendrik Jebens | Manuel Guinard Grégoire Jacq | 4–6, 6–2, [7–10] |
| Win | 3–6 | Aug 2023 | Augsburg, Germany | Clay | Hendrik Jebens | Constantin Kouzmine Volodymyr Uzhylovskyi | 6–2, 6–2 |
| Win | 4–6 | Sep 2023 | Como, Italy | Clay | Hendrik Jebens | Filip Bergevi Mick Veldheer | 6–3, 6–4 |
| Win | 5–6 | Sep 2023 | Bad Waltersdorf, Austria | Clay | Hendrik Jebens | Marco Bortolotti Francesco Passaro | 6–1, 6–2 |
| Win | 6–6 | Oct 2023 | Orléans, France | Hard (i) | Hendrik Jebens | Henry Patten John-Patrick Smith | 7–6$^{(7–5)}$, 7–6$^{(14–12)}$ |
| Loss | 6–7 | Nov 2023 | Ismaning, Germany | Carpet (i) | Hendrik Jebens | Sriram Balaji Andre Begemann | 6–7$^{(4–7)}$, 4–6 |
| Loss | 6–8 | Mar 2024 | Lugano, Switzerland | Hard (i) | Hendrik Jebens | Sander Arends Sem Verbeek | 7–6$^{(11–9)}$, 6–7$^{(1–7)}$, [8–10] |
| Win | 7–8 | May 2024 | Mauthausen, Austria | Clay | Hendrik Jebens | Ryan Seggerman Patrik Trhac | 6–4, 6–4 |

## ITF World Tennis Tour finals
### Doubles: 11 (5–6)

* Finals by surface
* Hard (1–4)
* Clay (3–2)
* Carpet (1–0)
| Result | W–L | Date | Tournament | Surface | Partner | Opponents | Score |
| Win | 1–0 | Oct 2015 | Ismaning, Germany | Carpet (i) | Alexander Erler | Kevin Krawietz Tim Sandkaulen | 2–6, 7–5$^{(7–5)}$, [10–8] |
| Loss | 1–1 | Oct 2021 | M15 Lubbock, United States | Hard | Sven Lah | Sekou Bangoura Gijs Brouwer | 4–6, 6–4, [5–10] |
| Loss | 1–2 | Nov 2021 | M25 Harlingen, United States | Hard | Gabi Adrian Boitan | Francis Alcantara Mark Whitehouse | 6–7$^{(3–7)}$, 7–5, [7–10] |
| Loss | 1–3 | Feb 2022 | M25 Glasgow, United Kingdom | Hard (i) | Charles Broom | Gijs Brouwer Aidan McHugh | 6–4, 6–7$^{(1–7)}$, [4–10] |
| Loss | 1–4 | Apr 2022 | M15 Monastir, Tunisia | Hard | Tim Sandkaulen | Szymon Kielan Michał Mikuła | 6–7$^{(4–7)}$, 7–6$^{(7–2)}$, [2–10] |
| Win | 2–4 | Apr 2022 | M15 Monastir, Tunisia | Hard | Charles Broom | Li Zhe Bu Yunchaokete | 7–5, 2–6, [10–8] |
| Win | 3–4 | May 2022 | M15 Meerbusch, Germany | Clay | Tim Sandkaulen | Miguel Fernando Pereira Gabriel Roveri Sidney | 7–6$^{(7–5)}$, 6–4 |
| Win | 4–4 | May 2022 | M25 Most, Czech Republic | Clay | Tim Sandkaulen | Marek Gengel David Poljak | 6–3, 4–6, [10–7] |
| Loss | 4–5 | Jun 2022 | M25 Arlon, Belgium | Clay | Tim Sandkaulen | Anirudh Chandrasekar Vijay Sundar Prashanth | 6–7$^{(5–7)}$, 4–6 |
| Win | 5–5 | Jul 2022 | M25 Kassel, Germany | Clay | Tim Sandkaulen | Tom Gentzsch Leopold Zima | 6–4, 6–2 |
| Loss | 5–6 | Aug 2022 | M25 Wetzlar, Germany | Clay | Tim Sandkaulen | Benjamin Hassan Tristan Lamasine | 4–6, 3–6 |