Maddison Keys and Sloane Stephens will face off in the US Open final, after both won their semi-finals on Friday morning AEST.

Keys was far too good for compatriot Coco Vendeweghe, winning 6-1, 6-2.

Meanwhile, Stephens played out an epic three setter with veteran Venus Williams, eventually prevailing in a topsy-turvey match, 6-1, 0-6, 7-5.

The match will be the first All American women's decider since 2002.

At 37 years of age, Williams would have competed to become the oldest female to win a Grand Slam title in the Open era had she won.

Both Stephens and Keys are aiming to their first Grand Slam titles.