McIlroy finished second in the European Tour order of merit
World number 10 Rory McIlroy has withdrawn from the Sun City Challenge in South Africa due to a stomach virus.
The 20-year-old, making his debut in the 12-man invitational event, had shot a one-over-par 73 followed by a four-over 76 in the opening two rounds.
The Northern Irishman has been troubled by the virus since last week's World Cup of Golf in China.
Sunshine Tour communications manager Michael Green told reporters McIlroy was suffering from "a stomach ailment".
McIlroy finished second in the European Tour's Race to Dubai order of merit, narrowly edged out by Englishman Lee Westwood.
However, McIlroy's third place at the Dubai World Championship saw him move up from 13th to 10th in the latest world rankings, making him one of only two players in their 20s - along with Spain's Sergio Garcia - in the top 10.