Marko Tkalec defeated Nuno Marques 6-2 6-4 in the Estoril q16 on clay. The upset overturned the form book — Nuno Marques came in leading the head-to-head 1–0, but Marko Tkalec had been the form player, winning 5 of their last 5 on clay. Marko Tkalec claimed a first win over Nuno Marques in two meetings, narrowing the head-to-head to 1–1.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 1999-02-22 | Croatia F2 | R32 | hard | Nuno Marques | 7-6 6-2 |