The world No. 5 has not been in top form since experiencing a wrist injury during the clay season.
“It's been tough to be on rhythm and [be] confident,” he said.
Initially aiming to secure a spot at the ATP World Tour Finals, he now appears to be weighing whether to stick to his schedule or simply wrap up his season.
"I cannot say now what I'm going to do during the next month," Nadal told reporters during his post-match press conference in Shanghai. "I'm not 100 percent sure about my calendar, the things I need to do to be ready for the next year ... I need to speak to my team. I need to speak to my uncle, too."
Nadal, who is in a tight race with Gael Monfils, Dominic Thiem and Tomas Berdych for a spot at the ATP Finals, needs to play events and add ranking points if he has any chance of making it to London. Yet he’s aware that this stretch of the season—the Asian swing followed by indoor tournaments—has traditionally been his least favorite period.
"It's a tough part of the season for me,” he said. “The tournaments are difficult. Surfaces are difficult.”
Unhappy with his game, he suggested taking additional time off to train, which could be more valuable than match play.
“Sometimes [continuing to compete] is not the solution,” he said. “Sometimes the solution is practice, and stop, and [continue the] process of training. And maybe it's an opportunity to do that. I'm not sure."
The Spaniard is next scheduled to play the ATP event in Basel in two weeks, and he said he could still compete there, as no decisions have been made. He is also scheduled to play the Paris Masters the following week.
But whatever he decides, his primary goal during the rest of the season will be to get into shape for next year. And he firmly believes that he’ll be ready to go for 2017.
"I have the confidence that I'm going to do it," said Nadal.
Nadal is No. 7 in the Tour Finals standings.