Madison Keys and Sloane Stephens will meet in the first all-American women's final at the US Open in 15 years.
The pair, close friends, will make their Grand Slam final debuts on Arthur Ashe Stadium at 21:00 BST on Saturday.
Both players returned at Wimbledon after having surgery this year, 15th seed Keys on her wrist and unseeded Stephens on her foot.
Serena and Venus Williams were the last Americans to line up against each other in the US Open women's final in 2002.
Serena is absent this year after giving birth to her first child, and Venus was beaten by Stephens in the semi-finals.