Major champions Francesco Molinari and Padraig Harrington have withdrawn from next week's PGA Championship in San Francisco, tournament organisers said on Thursday.
Neither player has competed on the PGA Tour since it resumed from the COVID-19 shutdown.
The PGA Championship was originally scheduled for May before it was postponed due to the COVID-19 pandemic. It will be the first of three majors set to take place this year.
Harrington, a winner of three major titles and Europe's Ryder Cup captain, has been replaced by American Talor Gooch for the tournament at TPC Harding Park, organisers said in a statement.
Molinari, the 2018 British Open champion, has been replaced by Troy Merritt.
Eddie Pepperell, Lee Westwood and Y.E. Yang have already opted not to compete.