British number two Cameron Norrie reached the Atlanta Open semi-finals after compatriot Dan Evans missed out on a spot in the last four.
Norrie, 23, reached his third semi-final of 2019 with a 7-5 6-4 win over Australian Alexei Popyrin.
Norrie will face either American second seed Taylor Fritz or Serbia's Miomir Kecmanovic as he bids to reach the second ATP final of his career.
Evans, 29, suffered a straight-set loss to big-serving American Reilly Opelka.
Opelka, 21, hit 23 aces on his way to a 7-6 (7-3) 7-5 victory.
After edging the first set, Opelka fought back from 15-40 to break world number 55 Evans's serve for a 6-5 lead in the second and served out the match to love.
Opelka, ranked 57th, meets Australian Alex de Minaur in the semi-finals.
De Minaur, 20, progressed after compatriot Bernard Tomic retired as he trailed 6-2 3-0 after just 39 minutes.
Tomic, 26, called for the trainer at the end of the first set - seemingly indicating he felt pain in his torso when serving - and eventually decided he could not continue any more.
Earlier this month, Tomic was fined his full Wimbledon prize money of £45,000 for not meeting the "required professional standard" during his 58-minute first-round defeat by Jo-Wilfried Tsonga.