ATLANTA, July 19 (UPI) -- Two-time defending champ Mardy Fish sprained an ankle Thursday and was forced to withdraw while leading his second-round match at the BB&T Atlanta Open.
Fish, the No. 2 seed, was in front of Gilles Muller 6-4, 3-2 when he retired. His left ankle buckled while he was trying to return a drop shot during the fifth game of the second set.
He eventually finished out the game, but then said his ankle hurt too much for him to continue.
Muller's advancement put him in the quarterfinals against Matthew Ebden, who recorded 20 aces in defeating James Blake 6-7 (6-8), 6-4, 6-4.
Top-seeded John Isner also made it to the quarterfinals, rallying for a 4-6, 6-3, 6-4 decision over Ruben Bemelmans. Jack Sock ousted Steve Johnson 7-6 (7-5), 7-6 (7-5) to set up a match against Isner.
