S. Costoulas and G. Knutson are level 1-1 in their head-to-head since 2018 over 2 matches.
| Surface | S. Costoulas | G. Knutson |
|---|---|---|
| Hard | 1 | 1 |
| Date | Winner | Score | Event |
|---|---|---|---|
| Aug. 4, 2026 | G. Knutson | 2 - 0 | Warsaw · 1/16-finals · hard |
| April 2, 2025 | S. Costoulas | 2 - 1 | W50 Nantes · 1/8-finals · hard |