Dustin Johnson has withdrawn from the CJ Cup after testing positive for coronavirus.
The world number one was tested after notifying PGA Tour officials that he was experiencing symptoms.
J.T. Poston will now replace Johnson in the field at Shadow Creek this week as the American begins a period of self-isolation.
"Obviously, I am very disappointed," Johnson, who last competed at the U.S. Open in September, said in a statement issued by the PGA.
"I was really looking forward to competing this week but will do everything I can to return as quickly as possible.
"I have already had a few calls with the Tour's medical team and appreciate all the support and guidance they have given me."
Johnson was considered the favourite for the CJ Cup, having won three PGA Tour titles in 2019-20 to return to the top of the rankings.
He was crowned the PGA Tour Player of the Year for the second time shortly after winning the FedEx Cup for the first time.