Tiger Woods cast doubt on his participation at next month's Open Championship after withdrawing from the AT&T National event next week.
The 35-year-old had been planning to return to action at the tournament near Philadelphia, having been out since May with injuries to his left leg.
Woods revealed on social networking site Twitter that he was sitting out the AT&T due to "doctor's orders".
The Open, won by Woods three times, begins at Sandwich on 14 July.
Woods, who has 14 major titles to his name, has been beset by injuries since returning at the 2010 Masters from a five-month break following his much-publicised personal problems.
These caused him to miss last week's US Open, the first time he has missed the event since making his debut in 1995.
At this year's Masters he suffered a sprain to his knee that was twice operated on in 2008 and also a mild strain to his left Achilles tendon.
The former world number one, now ranked 17th, returned for the Players' Championship at Sawgrass on 12 May but withdrew after only nine holes of the opening round because of a recurrence of the problems he experienced at Augusta.
The American's Twitter message concluded: "Feeling stronger every day but not 100%".
However, his absence from the field means he has missed three of his usual events in the build-up to the Open at Sandwich, where he finished joint third when it was last played there in 2003.