Roger Federer and Novak Djokovic ran into a spot of bother at the French Open, dropping a set each and needing over three hours to reach the fourth round.

Seventeen-times grand slam champion Roger Federer saw off Russian Dmitry Tursunov 7-5 6-7(7) 6-2-6-4 and Serbian second seed Djokovic, chasing the only grand slam title to elude him, beat Croatian Marin Cilic 6-3 6-2 6-7(2) 6-4.

"I am relieved and happy to be through to the next round," said fourth seed Federer, who wasted 17 break points.

Tursunov, the 31st seed, played boldly but needed treatment on his leg in the third set and Federer set up a meeting with Latvia's Ernests Gulbis, who is rediscovering his best form after a free fall down the rankings.

Djokovic, one of three men to have beaten eight-times Roland Garros champion Rafa Nadal on clay this season, showed signs of frustration against Cilic.

He seemed in complete control when his 25th-seeded opponent forced a tiebreak that the six-times grand slam winner lost 7-2. Djokovic regained control, however, and sealed victory when Cilic double-faulted.

His next opponent will be either local favourite Jo-Wilfried Tsonga, the 13th seed, or Poland's Jerzy Janowicz.

Top three out

In the women's draw, third seed Agnieszka Radwanska was knocked out 6-4 6-4 by Croatian Ajla Tomljanovic, becoming the latest victim of a new generation of talent sweeping through the women's draw.

The top three seeds have now been sent packing following the first-round exit of Chinese Li Na and the second-round elimination of defending champion and world number one Serena Williams.

It is the first time since tennis turned professional in 1968 that the top three seeds in the women's draw have failed to qualify for the fourth round of a grand slam.

"After seeing the two first seeds go out, you kind of feel you can do this too," said the 21-year-old Tomljanovic.

Radwanska's defeat was another boost for 2012 champion and last year's runner-up Maria Sharapova, who takes on unseeded Argentine Paula Ormaechea later on court Philippe Chatrier.

Tomljanovic, who had failed to qualify for Roland Garros every year since 2010, will next meet Spanish 14th seed Carla Suarez Navarro after she ended the run of American teenager Taylor Townsend with a 6-2 6-2 win.

Tomljanovic was joined in the fourth round by former finalist Samantha Stosur of Australia, who beat Slovakian ninth seed Dominika Cibulkova 6-4 6-4.

Source: Reuters