Another top 10 seed in the U.S. Open women's draw is set to fall on Sunday when Maria Sharapova (fifth) faces Caroline Wozniacki (10th) on center court in the fourth round.
Roger Federer then faces unseeded Spaniard Marcel Granollers in the third round to cap daytime play on Arthur Ashe Stadium.
Sharapova and Wozniacki barely raised a sweat as they breezed through their third-round matches.
Russian Sharapova, a five-time grand slam champion who won the French Open in June, has a 5-2 head-to-head edge against Wozniacki, but both of the Dane’s victories came on hard-court surfaces.
Sharapova won the 2006 U.S. Open while Wozniacki got to the 2009 final before losing to Kim Clijsters.
Seeds are now in short supply in the women's draw, with only five of the top 10 left in the tournament.
Federer had his hands full at times in his third-round match against big-serving Australian Sam Groth but Granollers will present a different kind of challenge.
The Spaniard, whose best results this year have come on clay, won a five-setter against Ivo Karlovic in the second round, overcoming 31 aces by the Croatian.
In clashes between seeded players away from center court, Gael Monfils (20th) takes on Richard Gasquet (12th) in an all-French showdown, while Croatian Marin Cilic (14th) faces South African Kevin Anderson (18th).
(Reporting By Andrew Both in Cary, North Carolina; Editing by Peter Rutherford)