Rafael Nadal remains on course for a 10th French Open title with a straight-sets victory over fellow Spaniard Nicolas Almagro in the second round.

The sixth seed, 28, who had lost to Almagro once in 13 encounters, won 6-4 6-3 6-1 on Court Philippe Chatrier.

Top seed Serena Williams survived losing the first set to beat Germany's Anna-Lena Friedsam 5-7 6-3 6-3.

But fifth seed Caroline Wozniacki lost to Germany's Julia Goerges, ranked 72nd in the world, 6-4 7-6 (7-4).

And Petra Kvitova, 25, seeded fourth, recovered from the loss of the first set to overcome Spain's Silvia Soler-Espinosa 6-7 (4-7) 6-4 6-2.

2010 winner Francesca Schiavone won a mammoth battle of former champions, overcoming 2009 predecessor Svetlana Kuznetsova 6-7 (11-13) 7-5 10-8 in three hours 49 minutes.

The match featured 206 points - more than double the 95 that made up Irina-Camelia Begu's 6-2 6-0 win over Croatia's Ana Konjuh earlier in the day - and is the third longest women's singles match in French Open history.

The pair have form for lengthy contests.

At the 2011 Australian Open Italian Schiavone beat her Russian opponent 6-4 1-6 16-14 in four hours and 44 minutes, setting the record for the longest women's match in Grand Slam history.