Rafael Nadal and David Ferrer struggled in key moments but did enough to advance to the quarterfinals of the 2013 U.S. Open as both players won in four sets against separate opponents.

Nadal beat German Philip Kohlschreiber 6-7 (4), 6-4, 6-3, 6-1, while Ferrer defeated Serbian Janko Tipseric, 7-6 (2), 3-6, 7-5, 7-6 (3) in the fourth round of the final Grand Slam of the year.

Nadal took advantage of Kohlschreiber's unforced errors (49) and seized 5 break points to turn the tide after losing the first set. Similarly, Ferrer buckled up in the third and fourth sets relying on his effective 1st serve (68 of 93 or 73 per cent) to avoid the upset.

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In the next round, Nadal will be paired with another player from Spain, Tommy Robredo, who was the tormentor of Roger Federer. Meanwhile, Ferrer will meet Frenchman Richard Gasquet, who beat Milos Raonic in an 5-set classic, 6-7 (4), 7-6 (4), 2-6, 7-6 (9), 7-5.

In the women's draw, Ana Ivanovic battles 2nd seed Victoria Azaranka on Tuesday morning for the final quarterfinals slot. Quarterfinals action also begins on Tuesday when Ekaterina Makarova faces off with Na Li and Serena Williams takes on Carla Suarez Navarro. Roberta Vinci and Flavia Pennetta complete the quarters cast.