Vladimir Obradovic defeated Artem Sitak 6-3 6-4 in the Mexico F4 round of 32 on hard. The upset overturned the form book — Artem Sitak came in leading the head-to-head 1–0. Vladimir Obradovic claimed a first win over Artem Sitak in two meetings, levelling the head-to-head at 1–1.
Obradovic V. took it in straight sets.
Vladimir Obradovic beat Artem Sitak 6-3 6-4. Umpiry, "Vladimir Obradovic vs Artem Sitak — Mexico F4 Round of 32", https://umpiry.com/match/2011-05-23/obradovic-vs-sitak-mexico-f4-r32?utm_source=cite (as of 23 May 2011).