Image copyright Getty Images Image caption Peter Charles from the USA has tested positive for testosterone
Four golfers have tested positive for doping in the build-up to the South African Open.
John Daly, who was world number one in 1991 and is the longest-serving winner of the PGA Tour, will miss the competition at the Johannesburg Country Club from 24 to 28 September.
American Peter Charles, a former tour winner, was a late withdrawal.
European Tour chief executive Keith Pelley said it was the organisation’s “first formal case of a sportsman knowingly using anabolic steroids”.
South African Marcus Botha is facing a two-year ban after being found to have used the drugs diuretics and masking agents in the build-up to the tournament.
Only one golfer, American Eric Butorac, was suspended for life following a 2010 test.
Pelley said all four have been provisionally suspended until the outcome of their case, which was filed on Friday.
He said the player who failed the test would be “ashamed that he has placed the integrity of the game at risk”.
First staged in 1945, the South African Open is one of the oldest tournaments on the European Tour and has hosted more than 140 champions, including 14 of the world’s top-10.
Players from 10 of the top 12 tours in the world are now competing in the event.