Rafael Nadal dismissed talk that life has been easy for him so far at this year's French Open, insisting there is a "big test" every day.

The reigning champion booked his place in the quarter-finals at Roland Garros with victory against Maximilian Marterer on Monday, continuing a streak of straight-set wins at this year's tournament.

But Nadal, the overwhelming favourite to seal what would be his 11th French Open triumph, is not concerned that he is yet to face a significant adversary in the competition, having been worked hard by a determined Marterer.

"My big test is every day. This was [an] important test," he told a news conference. "I am in the quarter-finals and the biggest test now is the next round.

"I go day by day and I am not worried about if I have had a test or I haven't had a test. I just worry about trying to be at 100 per cent for the next day that I have to play.

"That's my goal and I know, if I make that happen, if I'm able to play with my highest intensity and with the right level, [while there] will be always a tough match, I can have my chances to keep going.

"Every day, you go on court. You can win; you can lose. That's the only thing that you need to be ready for."

The Spaniard is refusing to look further ahead than Diego Schwartzman in the last eight, with Nadal expecting a difficult clash.

"[Schwartzman] is number 12 in the world. It's a match against one of the best players of the world today, so what you expect is a very tough match and you need to be ready to accept that and fight for it," the Spaniard said.

"I know what I have to do - it is tough to make that happen, because he's so good - but I hope to be ready to play at my best, and let's see what's going on.

"He is always a tough player and it is always good to see him in the quarter-finals, because he's a good friend, a good person. He's a worker and I am happy to see him having all this success - hopefully not too much."

A grinning Nadal added, of Schwartzman: "I played with him at the academy, but I'm never going to invite him again. Every time he comes, he comes out much better."