After a rain-ravaged Wednesday, top players - like Angelique Kerber - had to play catch-up Thursday.
And while Kerber managed to survive her second round match, fellow Top 10 star Sara Errani did not.
Ana Ivanovic, a former World No.1 who is trying to climb back to the upper rungs, made it through.
And this year's only teenage WTA champion, Elina Svitolina, was just edged by Christina McHale.
And the youngest player in the draw, Donna Vekic, succumbed to Simona Halep in straight sets.
With the help of some sharp shoes, Serena Williams beat Galina Voskoboeva on Arthur Ashe Stadium.
Over on Louis Armstrong Stadium, Victoria Azarenka was taking on newly-returned Aleksandra Wozniak.
Azarenka was originally up 5-0, lost three games for 5-3, then cruised from there to win, 63 61.
Azarenka moved through to the third round, where she will take on her contemporary, Alizé Cornet.
Azarenka is now 15-1 in Grand Slams this year, only falling to Maria Sharapova at the French Open.
The Williams sisters overcame an inspired Spanish duo in their first match of the doubles event.
Caroline Wozniacki wowed the Arthur Ashe crowd at night with a 61 62 win over Chanelle Scheepers.