Czech second seed Tomas Berdych and US seventh seed Sam Querrey advanced to a semi-final match-up at the ATP Winston-Salem Open with three-set victories on Thursday.
Former Wimbledon runner-up Berdych ousted Belgian Steve Darcis 4-6, 6-2, 6-0 while Querrey outlasted Ukraine fourth seed Alexandr Dolgopolov 7-5, 4-6, 7-6 (7/3), firing 20 aces in the match to win after two hours and 11 minutes.
Berdych had to come from behind to beat Darcis on the hardcourts at Wake Forest University.
Querrey, who won a title last month in Los Angeles, has won 13 of his last 16 matches and leads the US Open Series standings.
Berdych is the sixth seed at the US Open and will begin play next week in the year's final Grand Slam tournament against Belgian David Goffin.
Querrey, seeded 27th at Flushing Meadows, will open against Taiwan's Lu Yen-Hsun next week and could see Berdych in the third round.
Dolgopolov, the US Open's 14th seed, will open against American Jesse Levine and could face defending US Open champion Novak Djokovic in the round of 16.
In the other side of the draw, French top seed Jo-Wilfried Tsonga cruised past sixth seeded Marcel Granollers of Spain 6-1, 6-2.
Tsonga hammered five aces and won 77 percent of his first-serve points in a 53-minute match.
"I'm very happy because I played a bit less than the two (previous) matches and also because I played very good tennis. For me, it's good. It's good for the rest of the tournament," said Tsonga.
Tsonga's victory booked him a berth in the semis against third-seeded John Isner who defeated Goffin 7-6 (7/5), 6-3 on Thursday.
Tsonga won the first five games of the match and broke Granollers two more times in the second set, going four for five on break point chances. This will be his first semi-final since Wimbledon where he lost to Andy Murray.
Defending champion Isner overpowered Goffin with 21 aces, winning 33 of 38 points on his first serve.