Alex Levy was cut from the field for the European Tour's Celtic Classic on Thursday after a friend he spent time with last weekend tested positive for coronavirus.
Tour chiefs announced they were withdrawing Levy from the tournament on the morning of the first round at Celtic Manor.
Levy, 30, is a five-time winner on the European circuit.
"Upon arrival in Wales on Tuesday, Levy returned a negative test as part of the European Tour's testing strategy and is exhibiting no symptoms," a Tour statement read.
"However, as a precaution, the European Tour has withdrawn him from this week's tournament and Levy now must self-isolate for 14 days in accordance with local health authority guidance."
Levy said: "I told the European Tour immediately after finding out that my friend tested positive. I informed them of my movements since arriving on site as I wanted to ensure the safety of my fellow professionals and their caddies."