Novak Djokovic will decide over the next couple of days whether he will pull out of the Japan Open.
The world No 1 returned to training following a shoulder injury earlier this week.
The Serbian had not taken to a tennis court since withdrawing from his US Open fourth-round clash with Stan Wawrinka while two sets down.
And Djokovic feels he may need more time to recover before he starts the defence of his Shanghai Masters title in a fortnight.
“I have been training without pain for two days and that makes me optimistic about the idea of fulfilling my calendar,” Djokovic said.
“Between today and tomorrow, I will decide if I play Tokyo, but I feel safe in Shanghai.”
Djokovic has entered next week’s Japan Open but he may instead take another week to recover from his shoulder issue.
The 16-time Grand Slam winner is defending 2,600 points in the remaining event this year.
After Shanghai, the 32-year-old plans to travel to the Paris Masters and ATP Finals at London’s O2 Arena.
And Djokovic will be looking to make amends for withdrawing from the US Open.
“I’m sorry for the crowd. They came to see a full match, but it wasn’t to be,” Djokovic said after pulling out of the US Open.
“I mean, a lot of people didn’t know what’s happening, so you cannot blame them [for booing].
“It is very frustrating. Of course it hurts that I had to retire.
“Some days the pain has been higher, some days with less intensity.
“Obviously I was taking different stuff to kill the pain instantly. Sometimes it works, sometimes it doesn’t.”
