JOIN USNadal books quarterfinal berth
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 quite at his fluent best after struggling in the early rounds but he is peaking ominously.
"I'm playing well but there are moments where I make a few mistakes in a row," the five-times winner told reporters.
"It's difficult to get a rhythm against Ivan because he has a good serve. I've improved my position on the court... but I have to hit the ball with a little more conviction."
Robin Soderling, who lost to Nadal in last year's final having beaten him in the last 16 in 2009, will meet the world number one again in the quarters after bashing Gilles Simon 6-2, 6-3, 7-6 on a stunned Court Philippe Chatrier.
There was some cheer for the French fans though as Gael Monfils roared back to overcome seventh seed David Ferrer 6-4, 2-6, 7-5, 1-6, 8-6 and progress to meet Roger Federer.
Australian Open runner-up Li, the first Chinese player to reach the quarterfinals of the claycourt slam, outlasted Czech ninth seed Petra Kvitova 2-6, 6-1, 6-3 at the start of another humid day with thunderstorms forecast for later.
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 with her dogged determination.
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. I didn't believe I could come back, because she has a huge big serve," said Li, whose nervous husband and ex-coach could not watch.
"So I don't know what happened. Maybe my husband left and then I could win six games in a row," she joked. Serbia's 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 quarterfinal 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. The second seed 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 red-hot world number two will have to lift the trophy if he is to break the American's mark at Roland Garros.
Federer could loom in the semis and victory there would give Djokovic the world number one spot whatever Nadal does. Another player with injury problems is fourth seed Andy Murray, who is due to play Serbia's Viktor Troicki in the fourth round later having appeared to have shrugged off an ankle injury suffered in his easy win over Michael Berrer on Saturday.
The Briton had a leisurely practice with no visible problems but faced 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.
The Monfils match then finished having been suspended due to bad light on Sunday. Women's emerging contender Victoria Azarenka beat Ekaterina Makarova 6-2, 6-3. The women's draw has been blown wide open by the top three seeds all crashing out.
Seventh seed Maria Sharapova was playing Agnieszka Radwanska in the fourth round with the three-time grand slam champion's title odds shortening as the most experienced name left.
Results (prefix denotes seeding): Men’s singles: Fourth round: 9-Gael Monfils (Fra) bt 7-David Ferrer (Esp) 6-4, 2-6, 7-5, 1-6, 8-6; 1-Rafael Nadal (Esp) bt Ivan Ljubicic (Cro) 7-5, 6-3, 6-3; Juan Ignacio Chela (Arg) bt Alejandro Falla (Col) 4-6, 6-2, 1-6, 7-6 (7-5), 6-2.
Quarterfinal: 2-Novak Djokovic (Ser) w/o Fabio Fognini (Ita).
Women’s singles (fourth round): 6-Li Na (Chn) bt 9-Petra Kvitova (Cze) 2-6, 6-1, 6-3; 4-Victoria Azarenka (Bel) bt Ekaterina Makarova (Bul) 6-2, 6-3.