Australian Jordan Thompson had squandered three match points to exit the Los Cabos Open in Mexico at the quarter-final stage.
A warm favourite in his match against world No.135 Brandon Nakashima, Thompson went down 6-3 4-6 7-6 (7-4).
Thompson had looked set for the semi-finals when he had the American teen down 0-40 on serve with a 5-4 advantage in the deciding set.
But Nakashima reeled off five consecutive points to hold serve before ultimately winning the tiebreak against the world No.63.
Meanwhile, compatriot Alex Bolt was also dispatched, going down to big-serving American John Isner 6-3 6-4.
Isner will meet Nakashima in one semi-final while the other winners from Thursday, Cameron Norrie and Taylor Fritz, will play in the other.