Great Britain will have to come from behind to reach the Billie Jean King Cup final after a battling Sonay Kartal fell to the United States' Emma Navarro to go 1-0 down.
Kartal, ranked more than 60 places below world number 18 Navarro, had looked on course for her third victory over a player ranked inside the top 20 this year after going a set and a break up.
But Navarro, who saved two set points against Kazakhstan's Yulia Putintseva in the quarter-finals, fought back to outlast Kartal 3-6 6-4 6-3 and give the US the lead.