Former champion Zach Johnson was the latest to withdraw from the British Open on Monday because he tested positive for the coronavirus.
Louis de Jager, one of 12 players who earned a spot at Royal St. George's through local final qualifying two weeks ago, also returned a positive COVID-19 test and withdrew.
The R&A said Ryan Moore, runner-up at the John Deere Classic in Illinois, chose not to accept the exemption for the highest finisher among the top five at the PGA Tour event.
That brings the number of players who have withdrawn or chosen not to take their spots in the field for the 149th edition of golf's oldest championship to 16.
READ MORE: Matsuyama withdraws from British Open
The British Open was the only major to be canceled last year because of the pandemic. It returns this year under strict protocols by the UK government, and some instituted by the R&A, such as prohibiting players from staying with anyone except their own small core of people.
Johnson, who won at St. Andrews in a playoff in 2015, was at the John Deere Classic and had to be tested before getting on a charter flight. He did not play the third or fourth round with any other player who is at the British Open.
The latest players to withdraw were replaced by Adam Long of the United States, Sam Horsfield of England and Dylan Frittelli of South Africa.
The field already is missing seven players from the top 75 in the world, unusual for a major.
READ MORE: Japan's Nasa Hataoka wins LPGA Marathon Classic
Masters champion Hideki Matsuyama at No. 18 was the highest-ranked player to withdraw. He had a positive COVID-19 test during the Rocket Mortgage Classic on July 2, and while he has gone through 10 days of self-isolation without symptoms, his tests keep coming back positive.
The PGA Tour had this issue a year ago with positive tests. U.S. health officials said PCR tests can pick up remnants of the virus even though it is no longer active. But under UK guidelines, Matsuyama would need to produce a negative test.
Two-time Masters champion Bubba Watson said he came in contact with a person who had a positive COVID-19 test and withdrew. Under the R&A requirements sent to players on June 22, anyone who is identified as a contact has to self-isolate and be withdrawn.
Other players cited international travel requirements (Kevin Na) or an emphasis on preparing instead for the Olympics (Sungjae Im, Siwoo Kim, Juvic Pagunsan). The men's competition in the Tokyo Olympics starts on 29 July.
Latest on Sportstar
- Heat vs Nuggets Live Score, Game 1: MIA 42-59 DEN; Denver leads at half-time - NBA Finals updates
- Fishing helped Altmaier down Sinner in 5-hour 26-minute French Open epic
- NBA planning to announce latest Ja Morant decision after Finals, Silver says
- Denver Nuggets vs Miami Heat LIVE Streaming Info: When and where to watch the NBA Finals?
- Why is the England vs Ireland Lord’s Test a four-day game?