UPDATE 4:25 ET: No. 2 Victoria Azarenka's match against No. 13 Ana Ivanovic has been postponed due to rain.
The rain will also delay the Williams sisters' third-round doubles match.
Roger Federer, scheduled to face No. 19 Tommy Robredo on Arthur Ashe, will face the Spaniard at Louis Armstrong Stadium. They'll take the court following the conclusion of No. 21 Simona Halep's match against Italy's Flavia Pennetta.
Alison Riske was also scheduled to conclude her match against Daniela Hantuchova on Arthur Ashe.
Play has been suspended at the US Open due to rain Monday in Flushing Meadows. This is the second time rain has stopped play, with the first delay coming Wednesday.
It is not immediately known how long play will be suspended.
The rain started just after noon ET, halting play in two women's singles matches. At the time, Daniela Hantuchova leads Alison Riske 6-3 4-4, and Flavia Pennetta leads Simona Halep 6-2 4-5.
Two men's doubles matches were also in progress.
Roger Federer and Rafael Nadal each have fourth round matches scheduled for later in the day Monday.
Roberta Vinci completed her match with Camila Giorgi prior to the delay. Vinci won easily, 6-4 6-2, moving on to the quarterfinals.