Rafael Nadal and Novak Djokovic moved one step closer to a mouth-watering French Open quarter-final after both players won their first-round matches in straight sets.

Nadal is chasing his 10th title at Roland Garros, but has suffered some disappointing results on clay in recent weeks, while Djokovic has been in superb form, losing only two matches so far this year.

Both players, however, encountered few problems in round one and Nadal admits he is eager to find consistency after beating French wild card Quentin Halys 6-3, 6-3, 6-4.

"I had some up and downs during the season, so it is normal that can happen here, but I am trying to avoid that," said Nadal, who will now face fellow-Spaniard Nicolas Almagro.

"I played a good match, a solid one. When I had some opportunities I seized them. The first four games in the first set were tough, I made some mistakes, but then afterwards I was able to hit my shots.

"I had some problems with my serve, but on the whole, it was okay. I dominated the game. I managed to play some strokes down the line, so I handled the match very well. It was a solid performance and I'm happy with it."

Top seed Djokovic, who has never won the French Open, is also safely through after he beat Finnish veteran Jarkko Nieminen 6-2, 7-5, 6-2.

The Serb looked briefly vulnerable when Nieminen was 5-3 up and serving for the second set but he hit back, winning the next four games in a row.

"It was a test," Djokovic said. "I was aware of the quality and experience of my opponent today, who has shown, and especially in the second set, why he's been around the tour and a successful, consistent player for so many years.

"He can play. He can swing through the ball and be very aggressive. He was the better player for most of the second set.

"I managed to come back and play some good shots, stayed patient, stayed calm. Overall it was a very solid performance."

Djokovic and Nadal have met six times in Paris and the Spaniard has come out on top on every occasion. Nadal's win yesterday was his 67th in 68 matches at the tournament.

"His record says enough about the quality of the tennis that he plays here," Djokovic said.

"It's without a doubt his most successful tournament. He loves playing on clay, especially here in Paris.

"Best of five sets, as well, that is playing in his favour because there are not many players who can compete physically with him.

"To accept the fact that you're going to have to play a lot of long rallies, you're going to have to win the points, he's not going to give them to you - he's one of the best defenders ever to play the game."

The upset of the day came on Court 1, where American Jack Sock knocked out 10th seed Grigor Dimitrov in straight sets.

It is the second consecutive year Dimitrov has lost in the first round in Paris as last year's Wimbledon semi-finalist lost 7-6 (9/7), 6-2, 6-3.

Fourth seed David Ferrer won in straight sets against Slovakia's Lukas Lacko, while Richard Gasquet, Marin Cilic and John Isner are also safely through.