World No. 1 Dustin Johnson has become the biggest PGA Tour name to date to test positive for COVID-19.The Tour confirmed the news on Tuesday and announced that the 36-year-old has withdrawn from this week’s CJ Cup held at Shadow Creek Golf Course in Las Vegas. “Obviously, I am very disappointed,” Johnson said in an official statement. “I was really looking forward to competing this week, but will do everything I can to return as quickly as possible. I have already had a few calls with the Tour’s medical team and appreciate all the support and guidance they have given me.”Alternate J.T. Poston replaced Johnson in the field. Per Bob Harig of ESPN, Johnson returned a negative on-site test on Sunday but experienced virus symptoms beginning that night. He took another test on Tuesday that came back positive.Johnson hasn’t competed on the Tour since last month’s U.S. Open. He’ll need to report no symptoms and return negative coronavirus tests to be cleared for the Zozo Championship in California that begins Oct. 22. Tony Finau previously had to withdraw from the Shriners Hospitals for Children Open held at TPC Summerlin in Las Vegas and the CJ Cup because of a positive test. Meanwhile, two-time U.S. Open and PGA Championship winner Brooks Koepka will play this week following a two-month absence from the Tour caused by lingering knee and hip issues.