New York - US Open finalist Sloane Stephens said she would have "passed out" if she had been told a month ago when her world ranking was 957 that she would be in a first Grand Slam title match so soon.
The 24-year-old American stunned veteran compatriot and two-time champion Venus Williams 6-1, 0-6, 7-5 in a thrilling semi-final on Thursday.
Stephens, now ranked at 83, will play either CoCo Vandeweghe or Madison Keys, both also of the United States, in Saturday's final.
"If someone had told me when I started my comeback that I would make two semi-finals and a Grand Slam final I would have passed out," said Stephens.
The American player missed 11 months of the season after undergoing foot surgery and only returned to the tour at Wimbledon.
Since then, she has racked up 14 wins in 16 matches, reaching the semi-finals in Toronto and Cincinnati before making a second career semi-final at the majors in New York.
"I have no words to describe my feelings and what it took to get here," she added.
"I also have no idea how I have done it... just hard work. I hung tough, gritted it out. I worked my tail off."
In a thrilling final set, Stephens was 2-0 ahead before 37-year-old Williams clawed her way back to 5-4.
In a dramatic eight-minute 11th game, Stephens pounced before claiming victory in the 12th with Williams finally undone by 51 unforced errors.
"We played some incredible points in the third set," said Stephens, who saluted Williams - celebrating her 20th anniversary at the US Open.
"I am honoured to play at the same time as one of the greats of the game. She is the most graceful, the most elegant player."
Williams, who made the Australian Open and Wimbledon finals this year, admitted Stephens had edged the crucial points.
"It was definitely well competed. She ended up winning more points than I did. That's what it adds up to," she said.