Novak Djokovic pulling out of the upcoming Paris Masters without giving an explicit reason provides more uncertainty about his plans for the rest of the season.
The 38-year-old Serb was hampered by injury in his most recent ATP tournament, the Shanghai Masters, where he lost to qualifier Valentin Vacherot in the semi-finals.
Djokovic also had to retire from his match against Taylor Fritz at the Six Kings Slam exhibition in Saudi Arabia last week.
On Tuesday, the 24-time major champion announced he had decided to withdraw from the Paris Masters, the final ATP 1000 event of the season which starts next week.