Wimbledon semi-finalist John Isner beat Mischa Zverev in the quarter-final of the Atlanta Open on Friday.
The 33-year-old, who lost a mammoth semi-final to Kevin Anderson at SW19 earlier this month, won 7-5 4-6 6-1.
Marcos Baghdatis lost to Matthew Ebden 3-6 2-6 as Ryan Harrison made it through to the last four after beating Hyeon Chung 6-7 (3/7) 6-2 7-6 (7/5).
British number two Cameron Norrie will face Harrison in the semi-final after his quarter-final opponent Nick Kyrgios retired in the second set.
Norrie won the first set 7-5 and took a 3-0 lead in the second before Australian Kyrgios pulled out due to injury after 52 minutes on court.
The German Open saw world number 12 Diego Schwartzman lose to world number 36 Leonardo Mayer 6-3 4-6 6-3.
Jozef Kovalik beat Thiago Monteiro 3-6 6-3 6-2 as world number eight Dominic Thiem lost 6-7 (5/7) 6-7 (7/9) to Nicolas Jarry.
Georgia's Nikoloz Basilashvili beat Pablo Carreno-Busta 7-6 (7/3) 6-4.
At the Swiss Open in Gstaad, Feliciano Lopez lost 6-4 6-3 to Matteo Berrettini and Jurgen Zopp beat Facundo Bagnis 3-6 6-4 6-3.
Laslo Djere and Roberto Bautista-Agut also progressed.