Nadal will return to action at the Mubadala World Tennis Championship in Abu Dhabi in five days' time after six months out with a knee injury.
"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 U.S. Open and the season-ending World Tour championships before returning to the practice court on November 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."
The first grand-slam event of 2013, the Australian Open, starts on January 14.
The 26-year-old Nadal, who won a record seventh French Open crown in May on his favoured clay, said winning matches was not his priority over the coming weeks and he was totally focused on making sure the knee had healed properly.
"My goal is not this week, nor even Doha (from December 31) or Australia," he said.
"My goal is to be in shape, get back to feeling completely fine and feeling completely prepared.
"My season, my real objective, is to be in perfect condition for Indian Wells and Miami (in March) and get to Monte Carlo (in April) with good feelings, to tackle the clay season in good shape.
"The last tournament I played in good shape was Roland Garros and I won it.
"The end of February or March is when I will feel good. That's when my season starts, that's when I'll tell myself that I am ready to win."
Nadal's athletic, aggressive playing style places huge demands on his muscles and joints and he has been sidelined several times by injuries during his 11-year career.
He said he had not considered the possibility he might be forced to retire because of the latest setback.
"No, no, no. I have not thought about that," he told ABC.
"Tennis is a sport that does not last forever," he added. "It's not like golf which you can play for 20 or 25 years without any problems.
"In tennis time is limited, that's the way it is. I am an optimistic type and I don't believe that I have forgotten how to play tennis during these past months."