Jack Sock defeated Denis Zivkovic 2-6 7-6 6-2 in the USA F25 qualifying round on hard. The upset overturned the form book — Denis Zivkovic came in leading the head-to-head 1–0. Jack Sock claimed a first win over Denis Zivkovic in two meetings, narrowing the head-to-head to 1–1.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 2010-07-12 | USA F18 | R16 | clay | Denis Zivkovic | 3-6 6-2 6-1 |
Averages over each player's completed matches in the selected window. ATP, WTA & Challenger.