"I need to see how it improves and how it reacts to the intensity and demands of playing with tennis players of such a high level," Nadal said in an interview with Spanish daily ABC.
After a shock defeat to Czech Lukas Rosol in the second round at Wimbledon in June, Nadal was diagnosed with a partial tear of the patella tendon and inflammation in his left knee and was unable to defend his Olympic title at the London Games.
The 11-times Grand Slam singles champion also missed the US Open and the season-ending World Tour championships before returning to the practice court on Nov 20.
Nadal said the knee was "still not 100 percent" and he was planning to ease back in slowly. "I am not thinking long term, I am just focused on the knee, seeing how it responds and then we'll see later on.
I want to be sure that it s completely ready to start competing in anger again, without any doubts. If I feel good in Abu Dhabi we'll continue but if not I'll take it calmly."