Britain's Dan Evans let slip a one-set lead as Frances Tiafoe completed a comprehensive turnaround to reach the Stockholm Open semi-finals.
Fourth seed Evans had looked to be heading into his third semi-final of the year but lost 1-6 6-1 6-1.
American eighth seed Tiafoe could face Andy Murray for a place in the final with the Briton taking on Tommy Paul later on Thursday.
It is the end of the tour season for Evans, who won a first title this year.
The 31-year-old had arrived in the Swedish capital on the back of successive first-round exits at his previous two events and having been overtaken by Indian Wells champion Cameron Norrie as British number one.