Rain again caused a series of delays, with officials about 8 p.m. Thursday cutting the day's schedule short.
While some matches were allowed to finish, several, including Nadal's versus Martin Klizan and seventh-seeded Richard Gasquet's pairing against Michal Przysiezny, were postponed until Friday. More rain, however, is in the forecast.
Between rain delays, Djokovic, the world No. 1, dispatched Guido Pella 6-2, 6-0, 6-2. Djokovic finished off seven of his 16 break opportunities. He saw only one break point among the 10 points he lost on serve.
No. 13-seeded Kei Nishikori got past Grega Zemlja 6-1, 5-7, 6-1, 6-4; 26th-seeded Grigor Dimitrov was a 6-1, 7-6 (7-4), 6-1 winner over Lucas Pouille; and No. 27 Fabio Fognini beat Lukas Rosol 6-2, 7-6 (7-3), 2-6, 6-1.