Guillermo Bujniewicz defeated Diego Lopez 7-5 7-6 in the Argentina F12 round of 32 on clay. The upset overturned the form book — Diego Lopez came in leading the head-to-head 1–0, but Guillermo Bujniewicz had been the form player, winning 5 of their last 10 on clay. Guillermo Bujniewicz claimed a first win over Diego Lopez in two meetings, narrowing the head-to-head to 1–1.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 2007-09-03 | Argentina F15 | R32 | clay | Diego Lopez | 6-0 6-3 |