The PGA Tour's Travelers Championship will go ahead despite three individuals testing positive for coronavirus.
Cameron Champ, Graeme McDowell's caddie Ken Comboy and Brooks Koepka's caddie Ricky Elliott have the virus and have withdrawn from this week's event in Cromwell, Connecticut.
PGA Tour commissioner Jay Monahan said the news acted as "stark reminder" to comply with safety measures.
Seven tests of the 2,757 conducted have been positive since the Tour's return.
In a statement on Twitter, four-time major winner Koepka said, he "didn't want to do anything that might jeopardise the health of any player in the field or his ability to compete".
He added: "The right thing to do now is to get home and support Ricky."
While Champ was the only player to test positive for Covid-19 at the pre-tournament screening, fellow Americans Webb Simpson and Chase Koepka have also elected not to play.
PGA chief Monahan outlined several further measures that are to be introduced, including additional testing, coaches being brought into the testing bubble and fitness facilities becoming available to players on site.
"We need to learn to live with this virus," Monahan added.
'I've done it myself'
Monahan's announcement came after players have been seen flouting social distancing rules since the Tour resumed.
Those indiscretions have included fist bumping at the end of rounds, while some players have been unable to modify spitting habits on fairways and greens.
A recommendation that only the golfer handles his clubs also seems to have been virtually ignored.
And Monahan has warned of the consequences for anyone found not following safety protocols.
"All of us have an extraordinary responsibility to follow those protocols, for any individual that does not there will be serious repercussions," he said.