Madison Keys played superbly to beat Coco Vandeweghe for the loss of just three games and reach her first Grand Slam final at the US Open.
Keys, seeded 15th, won 6-1 6-2 in New York and goes on to face unseeded Sloane Stephens in the final.
Stephens, ranked 83rd, beat Venus Williams in the first semi-final.
The pair will make their major final debuts on Saturday in the first all-American women’s final since Serena Williams beat Venus in 2002.
Keys’ coach, Lindsay Davenport, in 1998 was the last American woman outside the Williams family to win the title in New York.
She could not have asked for more from Keys in only her second Grand Slam semi-final, with the 22-year-old dominating 20th seed Vandeweghe in every aspect.
It was their third meeting in as many tournaments, and produced the same result as Keys made it 3-0 in their head-to-head.
The only concern was a thigh issue that required strapping, but she said afterwards: “I definitely started to feel it and was worried something more serious could happen.
“I felt like I needed it worked on sooner rather than later. I feel great right now, I don’t think I could feel better than I do right now.”
Keys won the first five games for the loss of four points in 13 minutes, her powerful game impressively under control as she made just two unforced errors in the set.
Vandeweghe, 25, managed to at least slow her compatriot’s progress in the second but was soon a break down, and when Keys leant into a backhand down the line to break again for 4-1 she let out a scream of delight.
Given her huge lead it came as a surprise when Keys took a medical timeout off court, and she returned seven minutes later with her right thigh heavily strapped.
It made no difference to the outcome, with Keys returning to hold serve twice more and sealing victory with an ace.
“I knew had to rise to the occasion and I’m just really happy to be in the final,” said Keys, who ended with 25 winners and just nine errors.