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By Julien Pretot
PARIS, May 31 (Reuters) - Eight-times champion Rafa Nadal produced yet another rock solid performance to see off Argentine Leonardo Mayer 6-2 7-5 6-2 and reach the fourth round of the French Open on Saturday.
The world No.1, who is undefeated at Roland Garros since his only loss in 2009, extended his record to 62-1 on the Paris clay having not dropped a set at this year's event.
The Spaniard made only five unforced errors in the first two sets - 10 in total - even though he was broken in the second as world No.65 Mayer showed his claycourt skills.
Nadal ended the contest with a service winner to set up a meeting with unheralded Serbian Dujan Lajovic, who beat American Jack Sock 6-4 7-5 6-3 and also has yet to drop a set.
Nadal, however, revealed he was suffering from back pains, although he refused to elaborate when quizzed on the matter.
"Well, I'd rather not talk about my back. I've reached week number two. I'll do my best. I'll play as best as I can," he told a news conference.
"I'll put up a good fight to try and win. You know, my back is not that important. It's not that important, because I wouldn't really like to give you too many details.
"I am the way I am, and I'm happy to have reached this level. I won a three-set match, which is important."
His uncle and coach Toni Nadal said: "It was a solid match against a good claycourt player.
"In the second set, after he broke he lost his focus a bit. But he managed to come back and play some good tennis."
Against Mayer, who this year reached the final at the Vina del Mar claycourt tournament, Nadal was quick out of the blocks, breaking in the third and fifth games to bag the opening set in half an hour on a sun-drenched Philippe Chatrier court.
He broke to love in the third game of the second set as Mayer seemed to be heading for a humiliating defeat.
Yet the Argentine broke back for 4-4 as Nadal's crosscourt passing shot clipped the net cord and went just wide.
Nadal broke decisively in the 11th game with a lob that landed onto the baseline before bagging the set with a stunning forehand passing shot.
The third set was a mere formality and Nadal wrapped it up with a forehand winner. (Reporting by Julien Pretot; Editing by Toby Davis)