Former champion Padraig Harrington has pulled out of next week's US PGA Championship.
Harrington, who lifted the Wanamaker Trophy in 2008, did not give a reason for his withdrawal but has not played competitively since the coronavirus pandemic forced golf to shut down in March.
The Ryder Cup captain wrote on his personal website: "After much deliberation, I have decided not to travel to next week's PGA Championship.
"As Covid-19 currently looks to be under control in Ireland, I am taking the prudent approach by following the guidelines and reducing the risk as much as possible by staying at home.
"I'm sure I'll be watching every shot on TV with great interest and hopefully I'll have many more years to play in the PGA Championship."
Former Open champion Francesco Molinari is also understood to have withdrawn from the year's first major at TPC Harding Park in San Francisco.
Molinari announced earlier this month that he and his family were moving from London to California, although he did say at the time his aim was to be back for the US PGA.
Lee Westwood and Eddie Pepperell have also made the decision not to travel to San Francisco, despite the late easing of quarantine restrictions for players and essential personnel.
Harrington and Molinari have been replaced in the field by Talor Gooch and Troy Merritt.