VALENCIA, May 15, 2026
Constantin Frantzen has quietly established himself among the world’s top doubles players. Currently ranked world No. 44, the 28-year-old German is now the fifth-highest ranked doubles player in Germany behind the established teams of Kevin Krawietz and Tim Pütz, as well as Jakob Schnaitter and Mark Wallner.
Since last summer, Frantzen has been competing alongside experienced Dutchman Robin Haase — a partnership that has already produced impressive results. The duo captured their first title together in Chengdu last September, marking Frantzen’s maiden ATP Tour triumph, and followed it up with finals in Montpellier and Rio de Janeiro this season, as well as a quarterfinal run at Indian Wells.
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This week, the pair are competing at the Copa Faulconbridge in Valencia. We caught up with Frantzen to discuss his partnership with Haase, life as a doubles player, and their goals for the future.
Tennis TourTalk: Constantin, how has the partnership with Robin Haase developed?
Constantin Frantzen: We’ve been playing together since Kitzbühel last year, so this is our first full season as a team. Robin is a very experienced player and there’s a lot you can learn from him — especially the calmness he brings onto the court. But he’s also a super cool guy off the court and it’s a lot of fun playing with him. I’m really looking forward to the rest of the season.
How did the partnership actually begin?
After I split from Hendrik Jebens, I was already in contact with Robin. At that point, though, I decided to go with the “younger option” and teamed up with Alexander Erler, who’s also an old school friend of mine. Unfortunately, things didn’t really work out and we separated fairly quickly.
Then I saw that Robin was available, so I contacted him. It didn’t even take an hour for him to decide, and after that everything moved very fast. From the start, we worked really well together. I’m enjoying tennis again and we’ve already achieved some great results.
Is there almost like a “phone book” among doubles players when looking for a new partner?
I’ve actually been lucky because I’ve mostly had long-term partnerships. I played with Hendrik for two years, with Alex for half a year, and with Robin it’ll already be one year in the summer. But yes, there’s definitely something like a doubles group chat where most of the top 120 players are connected. If you suddenly need a partner for a tournament, it’s pretty easy to find someone there.
Your recent partners — including Robin — have all been German-speaking players. Is that important for you?
Not really. I played college tennis in the United States for five and a half years, so I was surrounded by people from many different nationalities. For me, it doesn’t matter whether I communicate in German or English with my partner. Recently, it just happened naturally that most of my partners were German-speaking, but it’s not something I specifically look for.
Has Robin hinted at retirement yet?
At the beginning of our partnership, he made it pretty clear that he still wanted to play for another two or three years. Of course, you always have to consider physical condition and family life as well. But I really hope he keeps playing for a while longer.
What’s the dynamic like away from the court during tournament weeks?
We’ve definitely developed a friendship. Robin is 39, so he’s 11 years older than me. During the first four months, we were practically travelling nonstop together. After Acapulco things became a bit calmer and we stayed in North America for some training blocks together.
When we’re back home, everyone also does their own thing. We live quite far apart — I’m based in Augsburg and he lives in the Netherlands. But we’re already planning to prepare together for next season as well.
Is this your first time in Valencia?
Yes, actually it is. My coach and friend Jimmy Bendeck is here with me. He’s American, but he was born in Valencia. Part of his family still lives here, although it’s also his first time back in the city in about 15 years.
He spoke very highly of Valencia before we arrived. His mother comes here several times a year, so she knows the city really well. We definitely have a few interesting places on our to-do list this week.
What goals have you set for the rest of the season?
We want to finish inside the top 13 in the Team Race and break into the top 30 of the ATP rankings. I already got pretty close recently when I reached No. 34. Overall, though, I’m really happy with how the season is going.
The main thing is to keep improving, keep working and enjoy the journey.
Thank you.
Interview: Florian Heer
