Stian Klaassen
- Country
- Netherlands
- Date of birth
- 2003-04-19
- Ranking ATP
- 1307 · 8 points
- Ranking ATP (doubles)
- 887 · 45 points
- Season 2026
- 0–0; doubles 4–0
Recent matches
| Date | Tournament | Round | Opponent | Score | Result |
|---|---|---|---|---|---|
| 2026-09-21 | Tennis Warehouse Open | F | Vignesh Gogineni / Noah Zamora (with Christopher Papa) | 7-6 5-7 10-3 | won |
| 2026-09-21 | Tennis Warehouse Open | SF | Alafia Ayeni / Daniil Ostapenkov (with Christopher Papa) | 6-4 6-4 | won |
| 2026-09-21 | Tennis Warehouse Open | QF | Daniel Milavsky / Braden Shick (with Christopher Papa) | 6-2 7-5 | won |
| 2026-09-21 | Tennis Warehouse Open | R16 | Jack Vance / Jamie Vance (with Christopher Papa) | 4-6 6-2 10-8 | won |
| 2025-07-28 | Hagen | R16 | Erik Grevelius / Stefan Latinovic (with Fons van Sambeek) | 3-6 4-6 | lost |