Williams' acting principal Simon Roberts tested positive for COVID-19 on Wednesday and will miss this weekend's Turkish Grand Prix, the Formula One team said.
Williams, last in the championship with four races remaining, said Roberts had not travelled to Istanbul or been in close contact with any other members of the race team.
He had been negative on Monday but tested again after showing minor symptoms.
"Simon is feeling otherwise well but will now isolate for the required 10-day period as per UK national guidelines whilst supporting trackside operations remotely this weekend," the team said.
"Dave Redding, Team Manager, and Chief Engineer of Vehicle Design, Adam Carter, will assume his responsibilities on the ground in Turkey.