Tiger Woods says he still does not know if he will play at the Open, which begins on 14 July at Royal St George's.
The 35-year-old former world number one has been out of action since May with injuries to his left leg and is remaining cautious.
"I will come back when I'm 100%. I don't know when that's going to be," said the American.
"I'm just playing it by ear right now. I've not hit any balls yet. I want to be playing, but I'm not ready yet."
Woods, who has won 14 major championships, including three Open titles (in 2000, 2005 and 2006), has had a string of injuries since returning at the 2010 Masters from a five-month break following his much-publicised personal problems.
At this year's Masters he suffered a sprain to the knee that was operated on twice in 2008 and also a mild strain to his left Achilles tendon.
Woods, now ranked 17th in the world, 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 injury problems also caused him to pull out of the recent US Open, the first time he has missed the event since making his debut in 1995.
But he admitted he made a mistake by trying to return at Sawgrass: "It was a borderline call to play The Players. I wasn't quite 100% and I hurt myself there.
"There's not going to be a 50-50 call this time. I need to get my body ready where I can practice and play and apply it. But I'm 35, I'm not 65 - I've still got some years ahead of me and I feel my best years are still ahead of me."
Woods, who has not won a tournament since November 2009, finished joint third when the Open was last held at Sandwich in 2003.
He is still having treatment twice and sometimes three times a day and has also spoken to coach Sean Foley about the plan for when he is fit to play again.
"I've played injured before and been successful at it [at the 2008 US Open]. I didn't think this was anywhere near that, but it's time to have a different approach. I'm setting no timetable - I'm going to learn my lesson and apply it. I'm being smarter this time."