Mikhail Biryukov defeated Anton Zaitcev 3-6 7-5 6-2 in the Russia F12 quarter-final on clay. The upset overturned the form book — Anton Zaitcev came in leading the head-to-head 2–0. Mikhail Biryukov claimed a first win over Anton Zaitcev in three meetings, narrowing the head-to-head to 2–1.
Biryukov M. came through in three sets.
Mikhail Biryukov beat Anton Zaitcev 3-6 7-5 6-2. Umpiry, "Mikhail Biryukov vs Anton Zaitcev — Russia F12 Quarter-final", https://umpiry.com/match/2013-08-26/biryukov-vs-zaitcev-russia-f12-qf?utm_source=cite (as of 26 August 2013).