Steffi Graf defeated Martina Hingis 6-2 4-6 6-0 in the Philadelphia quarter-final on carpet. The upset overturned the form book — Martina Hingis came in defending the title. Steffi Graf extended the head-to-head to 2–1.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 1999-05-24 | Roland Garros | F | clay | Steffi Graf | 4-6 7-5 6-2 |
| 1999-02-02 | Tokyo | QF | hard | Martina Hingis | 3-6 6-2 6-4 |
Averages over each player's completed matches in the selected window. ATP, WTA & Challenger.