Rafa Nadal and Li Na had decent workouts before sealing spots in the French Open quarter-finals on Monday but winning machine Novak Djokovic did not need to hit a ball to fast-forward into the last four.

As the first rain spots of the tournament began to drip on fans zig-zagging their way among the Roland Garros boutiques and snack stalls, champion Nadal was criss-crossing centre court in his usual all-action style to beat Ivan Ljubicic 7-5, 6-3, 6-3.

The Spaniard is still not quiet at his fluent best after struggling in the early rounds but he is peaking ominously.

So is Australian Open runner-up Li who outlasted Czech ninth seed Petra Kvitova 2-6, 6-1, 6-3 on another humid day with thunderstorms forecast later. She is the first Chinese player to reach quarter-finals of the claycourt slam.

After a lightning-quick third-round victory over Sorana Cirstea, sixth seed Li was given a much tougher test but again impressed the tennis connoisseurs on Court Philippe Chatrier with her dogged determination and weight of shot.

She battled back from an early break in the third set to prevail and prompted the suited gentlemen in the galleries to tip their panama hats in appreciation.

"It was tough, like 3-0 down in the final set. Even myself, I didn't believe I could come back, because she has a huge big serve," Li, whose husband and ex-coach could not stand the pressure, told reporters.

"So I don't know what happened. Maybe just my husband left and I could win six games in a row," she joked.

Djokovic was already looking unstoppable in his bid for a first title at Roland Garros and now he will get an extra's day rest compared to the others in the men's draw.

His quarter-final opponent Fabio Fognini pulled out of Tuesday's slated match after failing to recover from a thigh injury sustained in Sunday's five-setter with Albert Montanes.

"My doctors said if I play tomorrow maybe it can be dangerous," flamboyant Italian Fognini said.

Serbia's red-hot second seed Djokovic is on a 41-match winning streak since the start of the year, just one behind John McEnroe's 1984 record.

His progression through the last eight will not count as part of the streak, officials confirmed, so the world number two will have to lift the trophy if he is to break the American's mark in Roland Garros. Roger Federer could loom in the semis.

Local favourite Gael Monfils reached the quarter-finals of the French Open with a 6-4, 2-6, 7-5, 1-6, 8-6 win over Spanish seventh seed David Ferrer on Monday.

The match was interrupted due to bad light on Sunday with the ninth-seeded Monfils 2-0 down in the fourth set.

He did not give much of a fight when play resumed on court Suzanne Lenglen, dropping the set in less than half an hour before regrouping.

Monfils opened a 5-2 lead in the decider but wasted two match points at 5-3 as Ferrer broke back. Monfils, however, ended the contest on his fourth match point by blazing a forehand passing winner on Ferrer's serve.

Twice runner-up Robin Soderling set up a return match with champion Rafa Nadal after battering home hope Gilles Simon 6-2, 6-3, 7-6 in the French Open last 16 on Monday.

The Swedish fifth seed, who lost to Nadal in last year's final having beaten him in the fourth round in 2009, quickly silenced the fervent French crowd on Court Philippe Chatrier with an early break and never looked back.

There was little guile to Soderling's play, just relentless accuracy and even a third visit from the physio in three matches to treat a finger blister failed to slow him down against the 18th seed, although he laboured to close out the tiebreak.

The quarter-final with five-times winner Nadal comes as the Spaniard struggles for his very best form on clay.

The Briton had a leisurely practice with no visible problems but faces a wait to get on Court Suzanne Lenglen with Juan Ignacio Chela, his possible last eight opponent, taking almost four hours to beat Alejandro Falla in five sets.

Women's fourth seed and emerging contender Victoria Azarenka faces Ekaterina Makarova before Murray's match is scheduled.

The women's draw has been blown wide open by the top three seeds all crashing out.

After twice men's runner-up Robin Soderling battles home hope Gilles Simon to see who meets Nadal, women's seventh seed Maria Sharapova takes on Agnieszka Radwanska in her fourth round tie on centre court with the Russian's title odds shortening.