Atlanta, GA (Sports Network) - Top-seeded American John Isner rallied from a set deficit to beat Belgian Ruben Bemelmans Thursday in second-round action at the Atlanta Open tennis event.
Two-time defending champion Mardy Fish retired from his opening match. Fish, second-seeded, was leading Luxembourg's Gilles Muller 6-4, 3-2 when he called it quits due to a left ankle injury on the hardcourts at Atlantic Station.
Fish, who received a bye into the second round this week, stumbled while trying to return a drop shot and his left ankle appeared to buckle as he approached the net. He then dropped his racquet and fell to the court.
The Minnesota native stayed on his back for about a minute before limping off the court for a short break. Fish returned to finish the fifth game of the second set with a pair of aces. But after he and Muller changed sides, Fish decided his day was over.
The 30-year-old Fish recently returned to the ATP World Tour after being sidelined for three months. He was slowed by fatigue-like symptoms and ultimately underwent a heart procedure called cardiac catheter ablation, which deals with misfiring electrical pulses in the heart.
Fish beat Isner, last week's Newport champion, in the last two Atlanta finales.
Isner fired 16 aces during his 4-6, 6-3, 6-4 victory Thursday night. Isner will next take on 19-year-old American wild card Jack Sock, who defeated fellow countryman Steve Johnson, 7-6 (7-5), 7-6 (7-5).
Meanwhile, Aussie Matthew Ebden fired 20 aces before coming back to beat fading 32-year-old American James Blake 6-7 (6-8), 6-4, 6-4. Ebden will meet Muller here on Friday.
The winner of this $477,900 tournament will pocket $86,270.
The Sports Network