Douglas Geiwald defeated Jacco Van Duyn 6-2 6-1 in the Great Britain 1 Masters 1 round of 32 on carpet. The upset overturned the form book — Jacco Van Duyn came in leading the head-to-head 1–0. Douglas Geiwald claimed a first win over Jacco Van Duyn in two meetings, narrowing the head-to-head to 1–1.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 1991-03-22 | USA 1 Masters 4 | R32 | clay | Jacco Van Duyn | 6-4 6-4 |