

Marta Kostyuk defeated Jessica Pegula 7-6 6-1 in the San Diego semi-final on hard. The upset overturned the form book — Jessica Pegula came in ranked #3, leading the head-to-head 4–2. Marta Kostyuk narrowed the head-to-head to 4–3.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 2026-04-21 | Madrid | R32 | clay | Marta Kostyuk | 6-1 6-4 |
| 2026-01-04 | Brisbane | SF | hard | Marta Kostyuk | 6-0 6-3 |
| 2025-09-24 | Beijing | R16 | hard | Jessica Pegula | 6-3 6-7 6-1 |
| 2025-03-18 | Miami | R16 | hard | Jessica Pegula | 6-2 6-3 |
| 2023-01-16 | Australian Open | R32 | hard | Jessica Pegula | 6-0 6-2 |
| 2022-08-15 | Cincinnati | R32 | hard | Jessica Pegula | 6-7 6-1 6-2 |
Averages over each player's completed matches in the selected window (130 vs 173). ATP, WTA & Challenger.
Performance in the biggest moments — break points, deciding sets and tiebreaks (0–100, higher is better). About
Kostyuk M.: 1 day rest · 1 match, 31 games (7d) · Pegula J.: 2 days rest · 1 match, 17 games (7d). Higher means fresher. About
Each player's serve crossed against the other's return, converted to expected hold of serve. Recent completed matches, ATP, WTA & Challenger. About
Per-surface Serve / Return Rating (0–100, percentile within the hard field, opponent-adjusted over 52 weeks). About