PGA Tour veteran Chad Campbell has withdrawn from this week's Rocket Mortgage Classic after testing positive for COVID-19, as have three Korn Ferry Tour players who were slated to play the TPC Colorado Championship at Heron Lakes.

Campbell, 46, was the first alternate for the 156-man field in Detroit but tested positive as part of the pre-tournament screening process. He has not played since missing the cut at Colonial three weeks ago and will now enter a period of self-isolation, while Alex Cejka moves up to first alternate.

Campbell has four Tour victories, including the 2003 Tour Championship, and he lost in a playoff at the 2009 Masters. He becomes the sixth PGA Tour player to test positive for COVID-19 in the last two weeks, joining Nick Watney, Cameron Champ, Denny McCarthy, Dylan Frittelli and Harris English.

"While the positive test result is unnerving, I am incredibly grateful to be asymptomatic and feel physically well, and my thoughts are with anyone dealing with COVID, directly or indirectly," Campbell said.

In addition to Campbell's result, the Tour also disclosed that three players - Brandon Wu, Taylor Montgomery and Jonathan Hodge - all tested positive ahead of this week's Korn Ferry event, which begins Wednesday. They become the first Korn Ferry players to test positive as part of the on-site screening process, which has tested 247 players since June 11.

Montgomery missed the cut at each of the two Korn Ferry events in Florida earlier this month, while Hodge finished T-62 at TPC Sawgrass three weeks ago. Wu has not played a Tour-sanctioned event since the AT&T Pebble Beach Pro-Am in February.