Top seeds Novak Djokovic and Rafael Nadal had little trouble advancing to the semifinal round of the 2013 U.S. Open while their semis opponents -- Stanislas Wawrinka and Richard Gasquet, respectively -- pulled off masterful upsets on their way to the final four of the last tennis Grand Slam of the year.

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Curiously, both 1st seed Djokovic of Serbia and 2nd seed Nadal of Spain have only lost one set for the duration of this tournament, highlighting their tournament of the field so far.

Meanwhile, 9th seed Wawrinka of Switzerland defeated higher seeds Tomas Berdych (5th) in the fourth round , 3-6, 6-1, 7-6 (6), 6-2 and Andy Murray (3rd) in the quarterfinals, 6-4,6-3, 6-2. Eighth seed Gasquet of France beat David Ferrer (8th) of Spain, 6-3, 6-1, 4-6, 2-6, 6-3.

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Djokovic leads Wawrinka in their all-time head-to-head match-up, 12-2. The most recent one was a 5-set classic at the 2013 Australian Open Round of 16 where Djokovic prevailed, 1-6, 7-5, 6-5, 6-7(5), 12-10

Nadal has the edge over Gasquet in their head-to-head winning all 10 matches against the Frenchman. Both Gasquet and Wawrinka are appearing in their first-ever semis appearance in any Grand Slam.

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