Nadal hasn't played since his shock defeat in the second round of Wimbledon to Lukas Rosol in June.
The news comes during a disappointing season for Nadal after he had to withdraw from the Olympics and the US Open after admitting he had a partial tear in his patella tendon.
"I will hopefully resume practice soon since I am making good progress with my recovery from injury," said Nadal.
Rafael Nadal could also miss Spain's Davis Cup final against the Czech Republic in November.