Gaston Arturo Grimolizzi defeated Guillermo Hormazabal 6-7 6-4 6-4 in the Chile F3 round of 16 on clay. The upset overturned the form book — Guillermo Hormazabal came in leading the head-to-head 3–0. Gaston Arturo Grimolizzi claimed a first win over Guillermo Hormazabal in four meetings, narrowing the head-to-head to 3–1.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 2013-04-22 | Italy F5 | R32 | clay | Guillermo Hormazabal | 6-1 7-5 |
| 2007-11-12 | Chile F5 | F | clay | Guillermo Hormazabal | 6-0 6-4 |
| 2006-11-20 | Chile F5 | SF | clay | Guillermo Hormazabal | 6-2 6-1 |
Averages over each player's completed matches in the selected window. ATP, WTA & Challenger.