Ana Ivanovic was one of the first winners of the day, rolling past Sofia Arvidsson, 62 62.
Liezel Huber and Lisa Raymond rallied from 4-1 down in the third set to win their first match.
Carla Suarez Navarro looked headed for an upset over Agnieszka Radwanska, building a 64 31 lead.
Agnieszka Radwanska even faced a point for a 64 41 deficit, but fought back to win, 46 63 60.
Kim Clijsters took the doubles court but couldn't win, leaving the mixed as her very last event.
Serena Williams was disappointed with her play but managed to beat Maria Jose Martinez, 62 64.
Sloane Stephens also had a struggle but managed to outfox German qualifier Tatjana Malek, 57 64 62.
Sofia Vergara, of Modern Family fame among other things, was in the stands for the night session.
Venus Williams took Arthur Ashe Stadium under the lights for the last second round match remaining.
Since the start of 2000, only one left-hander had beaten Venus Williams twice - Angelique Kerber.
And Angelique Kerber was her opponent on Thursday night, toughing out a marathon 62 57 75 victory.
Angelique Kerber got her WTA-leading 55th match win of the year - no one else has more than 50.