The American is the third-oldest player to qualify for the year-end event in its history.
Oct 21, 2017
Garbine Muguruza had already secured her spot in the singles field.
Sep 26, 2017
by Zach Cohen
Spurred by the crowd, the hard-hitting American overcame a late-night, third-set obstacle.
Sep 05, 2017
by Steve Tignor
She's joined in the quarterfinals by Vandeweghe, Venus Williams and Stephens.
Also, Svitolina will take on Keys and Dolgopolov will play Nadal.
Sep 03, 2017