Australia's Adam Scott, the 2013 Masters champion, withdrew from the US PGA Zozo Championship on Wednesday after testing positive for Covid-19, the tour announced.
The 40-year-old from Adelaide was going to make his first start since sharing 38th at last month's US Open. Instead, he will begin a self-isolation period under health and safety protocols.
"While it's difficult news to receive -- as I really looked forward to playing this week -- my focus now is on recovery for the final stretch of the fall," Scott said in a statement.
Scott will be hoping to get well in time to compete at the Masters, which was moved to November 12-15 in this year's coronavirus-disrupted schedule.
Scott, ranked 15th, took his most recent US PGA triumph in February at Riviera.
American Jim Herman, the first alternate, replaced Scott in the Zozo field, which tees off Thursday in the opening round at Sherwood Country Club.
Also missing from the Zozo field is world number one Dustin Johnson, who tested positive for Covid-19 before last week's CJ Cup at Shadow Creek in Las Vegas.
Johnson, still feeling low on energy, plans to play next at the Houston Open the week before the Masters.