Madison Keys battled past Pauline Parmentier of France 7-6(4) 6-4 to lead the US into their second consecutive Fed Cup final in Aix-en-Provence on Sunday.
Keys, who was named as a late replacement for CoCo Vandeweghe, rallied back from 4-1 down to claim the opening set before a decisive break in the ninth game of the second ensured the victory.
Keys’ victory handed the defending champions an unassailable 3-1 lead over France in the semi-final tie before the hosts won the dead doubles rubber.
The French pair of Amandine Hesse and Kristina Mladenovic edged Vandeweghe and Bethanie Mattek-Sands 6-4 3-6 10-6.
Earlier in the day, US Open champion Sloane Stephens thrashed Mladenovic 6-2 6-0 to collect her second singles victory this weekend.
Stephens was aided by 25 unforced errors from world number 20 Mladenovic, whose touch eluded her far too often in the match.
"That was a really good one. You never anticipate a scoreline like the way it turned out but it was really solid," Stephens said.
The Americans extended their winning record to 12-2 against the French.
Madison Keys sends US into second straight Fed Cup final