World number one Dustin Johnson has withdrawn from this week's CJ Cup at Shadow Creek after testing positive for Covid-19.
The American was due to feature in Las Vegas for his first event since last month's US Open but will now be replaced in the field by first alternate JT Poston.
A PGA Tour statement read: "Experiencing symptoms, Johnson notified PGA Tour officials and was administered a test, with the positive result forcing his withdrawal from the event.
"Johnson will have the PGA Tour's full support throughout his self-isolation period under CDC (Centers for Disease Control) guidelines."
Johnson told the tour's website: "Obviously, I am very disappointed. 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."
Dustin Johnson has withdrawn from THE CJ CUP @ SHADOW CREEK after testing positive for COVID-19. https://t.co/KgwhWvW8xJ— PGA TOUR (@PGATOUR) October 13, 2020
Earlier, South African Jbe Kruger was withdrawn by the European Tour from this week's Scottish Championship after testing positive for the virus.
Kruger, who is asymptomatic, was tested upon his arrival at Fairmont St Andrews on Monday as part of the pre-tournament screening process and will now remain in self-isolation for a minimum of 10 days in accordance with mandatory Public Health Scotland and NHS Fife guidelines.
No other contacts were identified as part of the track and trace process other than Kruger's wife - and caddie - Denise, who will also be managed in accordance with Public Health guidelines.