Former champions Rafael Nadal and Serena Williams fell victim to the Roland Garros rain on Thursday when their French Open second-round matches were postponed for a day. Nadal had been due to face Argentina's Horacio Zeballos while Williams was to meet Germany's Julia Goerges. They were two of six singles matches cancelled -- and 22 in total -- after rain had washed out over four and a half hours of action on the fifth day of the tournament. Organisers saw over two hours lost on Wednesday. Play finally got underway at 1545 (1345 GMT) with Serbia's Jelena Jankovic, the fourth seed, opening proceedings on Court Philippe Chatrier against Estonian qualifier Kaia Kanepi. Serbian third seed Novak Djokovic was to tackle Japan's Kei Nishikori while fourth seeded Briton Andy Murray is scheduled to continue his second round clash against Argentina's Juan Ignacio Chela, which was suspended on Wednesday. 