Top seed Jessica Pegula staged a final-set rally to defeat Russian ninth seed Ekaterina Alexandrova 6-2, 2-6, 7-5 and reach the final of the WTA Charleston Open clay court tournament on Saturday.
Pegula, who ousted defending champion Danielle Collins in Friday's quarterfinals, looked to be in trouble after falling 4-2 behind in the decisive set to leave Alexandrova serving for a 5-2 lead.
But Alexandrova handed Pegula a lifeline with a shaky service game, and after finding herself down 15-40, gifted her opponent a break with a double fault.
Pegula then held to level at 4-4 and although Alexandrova also held for a 5-4 lead, Pegula was clearly in the ascendant.
The American leveled on serve at 5-5, and then grabbed a crucial break in the 11th game for a 6-5 lead to leave her serving for the match.
Pegula soon held two match points at 40-15, and although Alexandrova saved the first with a crosscourt forehand into the corner, Pegula lasered a backhand down the line to clinch victory.
"That was a tough match – it wasn't the prettiest," said Pegula, adding that blustery conditions had caused problems for both players.
"It was really windy – there were some awkward shots and we were both very uncomfortable," she said. "On some short balls and low balls, it was kind of swirling. I was just trying not to get frustrated."
Pegula will now face Sofia Kenin in Sunday's final. Kenin advanced after semifinal opponent, eighth-seeded Amanda Anisimova, retired hurt in the first set.
Anisimova needed a medical timeout trailing 2-1 in the first set after appearing to suffer a hip injury. The American was always struggling for mobility from that point and retired after falling 5-2 behind.
"It's never nice to see," Kenin said of her opponent's injury. "I felt like she was struggling, so you try to keep it as respectful as possible, taking it point-by-point.
"It's unfortunate for this to happen."