Amelie Mauresmo, the 22nd seed, is out of the French Open after she sank to a disappointing 6-3 6-4 defeat by Carla Suarez Navaro on Philippe Chatrier court.

Mauresmo has won Wimbledon and the Australian Open but is still to go beyond the quarter-finals in Paris and the defeat continued a miserable 2008.

Meanwhile Jelena Jankovic, the third seed, blamed heavy balls and the humid weather for the arm injury she suffered midway through her second-round defeat of Marina Erakovic at the French Open today.

The Serbian hurt her right forearm at the start of the second set but fought on to seal a 6-2 7-6 (7/5) win and set up a clash with 28th seed Dominika Cibulkova.

After winning the first set quite comfortably, Jankovic started having problems in the fifth game of the second. The arm was massaged and Jankovic took some painkillers before continuing, eventually clinching the set on a tie-break to eliminate New Zealander Erakovic, ranked 80 in the world.

Jankovic, 23, said: "It happened at the start of the second set and gradually got worse and worse.”

Slovakia's Cibulkova had earlier defeated Milagros Sequera 6-3 6-0 in 53 minutes on Court Five.

Venus Williams, the eighth seed, was also an early winner in overcast conditions on the fifth day, beating Tunisia's Selima Sfar 6-2 6-4. The American took the opening set at the first time of asking in 35 minutes but had more trouble in the second. She will next play 26th seed Flavia Pennetta, from Italy, who beat Anastasia Pavlyuchenkova 3-6 6-1 6-1.

Katarina Srebotnik, the 27th seed from Slovenia, set up a third-round clash with fifth seed Serena Williams by brushing aside Ekaterina Makarova in straight sets.

Elsewhere, qualifier Iveta Benesova beat Shuai Peng 6-4 6-3 to go through to the third round where she will play fellow Czech Petra Cetkovska, who defeated Russia's Galina Voskoboeva 7-5 6-3. Another seed to fall was Japan's Ai Sugiyama (31), who lost 6-0 7-5 to Olga Govortsova.