Denis Zivkovic defeated Jack Sock 3-6 6-2 6-1 in the USA F18 round of 16 on clay. The upset overturned the form book — Jack Sock came in leading the head-to-head 1–0. Denis Zivkovic claimed a first win over Jack Sock in two meetings, narrowing the head-to-head to 1–1.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 2009-10-12 | USA F25 | QF | hard | Jack Sock | 2-6 7-6(4) 6-2 |
Averages over each player's completed matches in the selected window. ATP, WTA & Challenger.