Shane Lowry is still due to take part in the event.
Graeme McDowell has confirmed his withdrawal from this week's Travelers Championship on the PGA Tour.
The 2010 US Open winner is to stand down after his caddie Ken Comboy tested positive for Coronavirus.
He's the second player to withdraw from the tournament after golfer Cameron Champ tested positive for Covid-19.
McDowell says he's withdrawing from the event "for the protection of the field", as well as his own physical and mental well-being.
Cameron Champ has withdrawn from the Travelers Championship after testing positive for COVID-19 during pre-tournament screening on Tuesday.https://t.co/NFi0K13oqi— PGA TOUR (@PGATOUR) June 23, 2020