Denny McCarthy tested positive for coronavirus at the Travelers Championship and playing partner Bud Cauley has also withdrawn.
Despite three positive coronavirus tests, Rory McIlroy dismissed those who suggested the Travelers Championship be called off.
Canadian Mackenzie Hughes opened up a three-stroke lead after the Travelers Championship first round.
After finishing seventh at the RBC Heritage, Brooks Koepka was hopeful about his form and fitness for the rest of 2020.
The RBC Heritage is unlikely to see Rory McIlroy on a regular basis as the world number one thinks other events suit him better.
American Webb Simpson continued his good form this year, winning the RBC Heritage.
World number one Rory McIlroy discussed Nick Watney's positive COVID-19 test following Saturday's third round.
Brooks Koepka is one of 17 players sitting within three shots of Webb Simpson, Tyrrell Hatton, Abraham Ancer and Ryan Palmer.
Nick Watney's close contacts have tested negative for coronavirus, as Justin Thomas described Hilton Head Island as "an absolute zoo".