Padraig Harrington has pulled out of this week's BMW PGA Championship at Wentworth because of a shoulder injury.
Three-time major winner Harrington withdrew from the European Tour's flagship tournament after playing just two holes of his first round.
The Dubliner also withdrew from Wednesday's pro-am competition.
The 43-year-old, who has returned to the top 100 in the world rankings this year, could now be doubtful for next week's Irish Open at Royal County Down.
The world number 83 had indicated before his round on Thursday that his withdrawal was "definitely a possibility", despite receiving physiotherapy treatment.
"It is like frozen shoulder. I am struggling to lift my arm," explained the Irishman, who won the PGA Tour's Honda Classic in early March.
The Florida triumph was his first win on either the PGA Tour or European Tour since his 2008 USPGA victory at Oakland Hill.
His withdrawal from the Wentworth event marks the first time he has pulled out of a tournament because of injury in his 20-year career.
The Irishman said that he felt the problem while in the gym in Tuesday but had opted to continue his fitness session.
"I probably should have stopped doing the exercises," he added.
"I didn't feel so bad and I hit shots afterwards but it has really stiffened up overnight."