PHOTOS: Champion Li Na shocked, Sharapova survives

Defending champion Li Na was shown the door while Maria Sharapova remained on course for a maiden title after the fourth round of the French Open on Monday.

The seventh seeded Na was beaten Kazakh qualifier Yaroslava Shvedova 3-6, 6-2, 6-0.

Meanwhile Sharapova managed to scrape past Klara Zakopalova 6-4, 6-7 (5), 6-2 to move into the last eight.

The Russian star, who had reached the last 16 for the loss of just five games and having spent less than three hours on court, had to dig deep to get it past the resilient Czech. 

The 30-year-old Zakopalova, ranked 44th, capitalised on some poor serving by the Russian to force a decider. However, in the final analysis it was Sharapova's experience that helped her through.

Sharapova, continuing on in Paris where she left off in Rome, now has a 10-match streak and with most seeds having fallen by the wayside remains the firm favourite to win the lone major missing from her kitty. 

Local favourite Jo-Wilfried Tsonga kept his eye on the prize to reach the French Open quarter-finals for the first time with a 6-4, 7-6, 3-6, 3-6, 6-4 win against Swiss 18th seed Stanislas Wawrinka on Monday.

The fifth-seeded Frenchman was 4-2 up in the decider when the match was interrupted by dusk on Sunday and dropped serve when play resumed on Court Philippe Chatrier.

Tsonga, the last Frenchman to reach a grand-slam final, at the 2008 Australian Open, wrapped it up by breaking Wawrinka with a forehand winner after four hours and six minutes.

He will face world number one Novak Djokovic of Serbia on Tuesday for a place in the last four.

David Ferrer was deafened but not stirred as he silenced shrieking Spaniard Marcel Granollers with a 6-3, 6-2, 6-0 demolition job in the fourth round of the French Open on Monday.

While fans are accustomed to the likes of Maria Sharapova and Victoria Azarenka ratcheting up the decibel levels, Granollers proved that grunting was not confined to the women's game.

Unusually, Granollers often groans well after the ball has flown off his racket but despite his antics, a focussed Ferrer reached the last eight for the third time.

Sixth seed Ferrer has now won four straight-set matches, dropping only 25 games, and will be favourite to make it through to his first semi-final here when he faces either fourth seed Andy Murray or local hope Richard Gasquet.

Nicolas Almagro kept up the ruthless run by Spaniards at the French Open as he reached the quarter-finals with a 6-4, 6-4, 6-4 hammering of Serbian eighth seed Janko Tipsarevic on Monday.

Almagro, the 12th seed, is one of three players in the men's draw yet to drop a set and coincidentally they all hail from Spain.

While six-times champion Rafa Nadal will be aiming to preserve his perfect record when he takes on Argentine Juan Monaco in a fourth-round contest later on Monday, David Ferrer has also reached the last eight by winning 12 successive sets.

Almagro kept the bearded Tipsarevic on his toes throughout the two hour 13 minute encounter and blew a kiss skywards after ending the Serb's ordeal with a driving forehand winner.

Almagro will next face the winner of the Nadal-Monaco match.

Juan Martin del Potro edged past Tomas Berdych in a battle of big-hitting baseliners to book his spot in the French Open quarter-finals, winning 7-6, 1-6, 6-3, 7-5 on Monday.

After the match was suspended at the end of the third set due to bad light on Sunday evening, the ninth-seeded Argentine returned to wrap up victory in three hours 26 minutes.

Del Potro exchanged clubbing flat forehands with his opponent in a first-set struggle that lasted over an hour before Berdych struck back emphatically in the second.

The Argentine, who will play Roger Federer in the quarters, returned to the ascendancy in Sunday's evening gloom before breaking decisively in the 12th game of the fourth set.

In the biggest upset of the tournament so far, defending women's champion Li Na was knocked out in the fourth round on Monday by Kazakh qualifier Yaroslava Shvedova 3-6, 6-2, 6-0.

After taking the first set, the Chinese seventh seed collapsed, taking only two games out of the next 14.

Last year's champion made 41 unforced errors as she spectacularly lost control of a match in which she had looked to be cruising towards victory.

Doubles specialist Shvedova, ranked 142 in the world in singles, will now play the winner of Varvara Lepchenko's match against Wimbledon winner Petra Kvitova in the quarter-final.