Los Angeles - American John Isner showed why he is playing some of the best tennis of his career on Friday, beating Mischa Zverev 7-5, 4-6, 6-1 in the quarter-finals of the Atlanta Open.
Isner needed one hour and 37 minutes on Stadium Court to oust Zverev and reverse a run of defeats to the seventh seeded German.
Zverev had won all three of his matches against Isner last year. But the 33-year-old Isner has been rising up the rankings as he levelled their career head-to-head rivalry at 3-3.
"It was a weird match. The balls were bouncing everywhere, it was tough to control. I was happy to get through in three sets," Isner said.
The 6-foot-10 Isner is at number nine in the ATP world rankings. He reached a career-best No. 8 last week after making it to the semis of Wimbledon.
Isner will next face fourth seed Matthew Ebden, who breezed past Marcos Baghdatis 6-3, 6-2 in one hour, 12 minutes.
The Aussie is into his second semi-final of the season, following a run to the final four at the Libema Open.
Isner is now two victories from winning his second title of the year.
The match shaped up to be a service battle as both players needed just a break each to split the first two sets.
Isner ended up losing just two points (38/40) on is first serve and this was the fourth straight contest they went to a deciding set.
Ebden, 30, has not dropped a set this week, saving the only break point he faced to eliminate Baghdatis.
Isner has won three of his four career matches against Ebden, but the Aussie defended his home turf with a four-set victory at this year's Australian Open.
In the other quarter-finals, Ryan Harrison outlasted Chung Hyeon 6-7 (3/7), 6-2, 7-6 (7/5) and Cameron Norris was leading 7-5, 3-0 in the second set when Nick Kyrgios retired due to a left hip problem.
Results from ATP Atlanta tournament on Friday (x denotes seed):
John Isner (USA x1) bt Mischa Zverev (GER x7) 7-5, 4-6, 6-1
Matthew Ebden (AUS x4) bt Marcos Baghdatis (CYP) 6-3, 6-2
Ryan Harrison (USA x8) bt Chung Hyeon (KOR x3) 6-7 (3/7), 6-2, 7-6 (7/5)
Cameron Norrie (GBR) bt Nick Kyrgios (AUS x2) 7-5, 3-0 retired