Simona Halep came into the US Open in top form. Now she's in her first second week at a Grand Slam.
The No.21-seeded Halep's fourth round berth came at the expense of No.16-seeded Maria Kirilenko.
Elsewhere, Flavia Pennetta reached the fourth round too, defeating No.27 seed Svetlana Kuznetsova.
No.26 seed Alizé Cornet pushed No.2 seed Victoria Azarenka to the limits on Louis Armstrong Stadium.
But Azarenka managed to win through, losing the first set in a tie-break but winning the next two.
Azarenka is now 15-1 in Grand Slams this year, only losing to Maria Sharapova at the French Open.
Carla Suárez Navarro, who made the fourth round on Friday, signed autographs on her day off.
No.13 seed Ana Ivanovic won a nail-biter against American qualifier Christina McHale, 46 75 64.
And Daniela Hantuchova saved three match points to beat Israeli qualifier Julia Glushko, 36 75 76(4).
Camila Giorgi - also a qualifier, from Italy - stunned No.6 seed Caroline Wozniacki at night.
The celebrities were out all day on Saturday, including Academy Award-winning actor Kevin Spacey.
Another famous actor - Winona Ryder - was also among the celebs attending the US Open tennis.
Ralph Macchio, best known for Karate Kid and My Cousin Vinny, is also a big tennis fan.
And Ashley Greene, who featured in the Twilight movies, was also among those coming to the tennis.
Henrik Lundqvist, Swedish professional ice hockey goaltender for the New York Rangers, was there too.