PARIS -- Men's world number one Rafael Nadal and his female counterpart Simona Halep won in straight sets to secure their places in the quarterfinals at the 2018 French Open on Monday.

Despite conceding a break at the start, 10-time champion Nadal swept Roland Garros debutant Maximilian Marterer of Germany 6-3, 6-2, 7-6 (4).

"6-3, 6-2 have been very positive 12 games for me. In the third, I had the chance at the beginning to have the break and probably take an important advantage to close the match, but didn't convert it. Then I had a couple of mistakes with my serve and suffered a tough third set," said Nadal.

Nadal will next face Argentine Diego Schwartzman, who rallied from two sets down to eliminate No. 6 seed Kevin Anderson in full sets.

Halep, in pursuit of her maiden Grand Slam title in Paris, met little resistance from Belgian Elise Mertens and conceded just three games for a 6-2, 6-1 victory in 59 minutes.