American Reilly Opelka upset John Isner with a 7-6 (7/2), 6-7 (5/7), 7-6 (7/5) victory in the second round of the Atlanta Open here.
The loss on Wednesday by the tournament's top seed gave Isner his earliest exit at this event in 10 appearances.
The 21-year-old Opelka saved three break points while serving at 4-5 in the third set, including two consecutively from 15/40 as he served his way out of trouble.
The unseeded Opelka also defeated Isner at the Australian Open and at the New York Open in February, where he went on to win his first ATP title.
“I was clutch on big moments in the match. First-set tie-break I played unbelievable, pretty much flawless, hit some great shots,” Opelka said.
“It’s so hard to play three tie-breaks with him because there’s just so much pressure, there’s so much stress for three hours straight. It’s tough. I’m thrilled to get through.”
Isner was the two-time defending champion and had reached the Atlanta final in nine of his 10 appearances.
“It’s his tournament. It always will be. Definitely a tough guy to beat in Atlanta,” Opelka said.
Divij to face Bryan brothers
Partnering Jonathan Erlich, India’s Divij Sharan will test his skills against the legendary Bryan brothers, Mike and Bob, in the ATP Atlanta Open quarterfinal clash here.
Sharan and Erlich came from behind to beat Miomir Kecmanovic and Robert Lindstedt 2-6, 6-3, 13-11 in the first round of the ATP 250 event.
The Bryans, who have won more than 100 ATP doubles titles together, ousted fellow American wild card pair of Christopher Eubanks and Donald Young 6-4, 6-2 in their opener.
In the bottom half of the draw, veteran Leander Paes and his partner Marius Copil made a first-round exit following a close 6-7(2), 4-6 defeat to British-American combination of Taylor Fritz and Cameron Norrie.
Prajnesh Gunneswaran, the only Indian featuring in the singles draw, had lost his first round on Wednesday.