Although the sixth-seeded Nadal had to save a break point in his opening service game, and was not always at his fluent best with his shot-making, he stepped up a gear in a dominant third set to secure his 13th win in 14 matches against Almagro.
Almagro showed admirable defensive qualities, saving three set points in the opening set. Nadal clinched it on serve with a crisp forehand winner and then broke Almagro at the start of the second set.
Nadal, dressed head to toe in electric blue, stood out on center court in somewhat gloomy and overcast conditions. He sealed victory in 2 hours, 19 minutes when Almagro stretched to return a powerful forehand down the line and swiped the ball out of court.
Meanwhile, Francesca Schiavone of Italy again showed more endurance than 18th-seeded Svetlana Kuznetsova, beating her 6-7 (11), 7-5, 10-8 in a match lasting nearly four hours to reach the third round.
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At the 2011 Australian Open, she beat the Russian player in the longest women's match, by time, in Grand Slam history -- a 6-4, 1-6, 16-14 contest that lasted 4 hours, 44 minutes. Schiavone saved six match points in that match, then converted on her third match point.
She sealed victory when Kuznetsova -- a two-time Grand Slam champion who won here at Roland Garros in 2009 -- attempted a forehand drop shot that sank into the net, bringing to an end a topsy-turvy match featuring brilliant winners but also some sloppy serving, with a total of 18 breaks of serve.
Schiavone tilted her head back in relief and then threw her arms up in the air in triumph after sealing victory.