Rory McIlroy has withdrawn from next week's Turkish Airlines Open, the first of the European Tour's three Final Series events.
No reason was given by the four-time major winner's manager when he informed Tour officials of the decision on Saturday.
McIlroy is currently contesting the WGC-HSBC Champions in China and had spoken of his desire to win at least one of his last three events this season - in Shanghai, Turkey and Dubai - to try to win the Race to Dubai for a third year in succession.
The 27-year-old world No 3, who is more than a million points behind Race to Dubai leader Danny Willett, was set to be the star attraction at the Regnum Carya Golf & Spa Resort in Antalya after Tiger Woods pulled out - the 14-time major winner saying he needed more time to work on his game after a long injury lay-off.
Earlier this month, European Tour officials investigated reports that the southern Turkish holiday resort region of Antalya was hit in a rocket attack.
Turkish media reported that two rockets were fired from a mountainous area close to the highway linking the city of Antalya to the resort town of Kemer.
No one was killed or injured in the attack, which hit a fishing company's storage house and open ground nearby.
It is understood the Tour received assurances from security experts that it was safe to stage the event, won last year by France's Victor Dubuisson.