PARIS — When it comes to playing on clay, Rafael Nadal's excellence is so striking that even the slightest problem can seem like a big deal.

For instance, being forced to save a grand total of two break points in one match at the French Open.

"First set I think was good level. Second one was good at the end, but in the middle of the set I had some problems with my serve, two break points in two games," Nadal said Thursday after beating Denis Istomin of Uzbekistan 6-2, 6-2, 6-0 to advance to the third round.

Istomin didn't convert either, of course. He then won even fewer points – only five in the six games – in the final set.

The win was Nadal's 47th in 48 matches at Roland Garros. His only loss came in 2009, when Robin Soderling beat him in the fourth round.

Besides that blip, Nadal has won six French Open titles, and one more will break the record he shares with Bjorn Borg.

But the second-seeded Spaniard isn't ready to sit back and relax. There are still some improvements to make.

"The serve is the first one. I think I improved the level of my serve during the match, but I started the match serving bad," Nadal said. "For the rest, more or less I have to be happy."

For Istomin, there wasn't much to celebrate against perhaps the best clay-court player of all time.

"He does everything on clay. Like everybody says, `King of Clay,'" Istomin said. "In the beginning, was a good match for me, too. Not many mistakes."

That didn't last.

Istomin ended up with 25 unforced errors while Nadal had only 17 – zero in the third set.

"It was a dream type of third set," said Nadal, who is 18-1 on clay this season.

With three titles, he's still worried about his game.

"I didn't really serve well when the match started, though," Nadal said.