Tiger Woods admits never being able to return to competitive golf is a possibility as he recovers from a fourth back operation.
The 14-time major champion said an arduous rehab process following the spinal fusion surgery he underwent in April had created uncertainty around whether his once remarkable career could continue.
Woods, 41, has not played a tournament since withdrawing prior to the second round of the Dubai Desert Classic in February.
Asked if there was a scenario in which he never competed again, Woods said: "Yeah, definitely. I don't know what my future holds for me."
The former long-time world No.1 ended a 15-month injury stint when he teed off at the Hero World Challenge in the Bahamas in December, before missing the cut at the Farmers Insurance Open in late January and playing one round in Dubai immediately after.
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Woods said a timetable on his return was not possible until upcoming six-month scans determined the success of the anterior lumbar inter-body fusion - a procedure designed to alleviate lower back and leg pain.
"My timetable is based on what my surgeon said," said Woods at the Presidents Cup in New Jersey, where he is an assistant captain to American team boss Steve Stricker.
"As I alluded to (on his website) last week, I'm (only) hitting 60-yard shots."
But it wasn't all doom and gloom for the Californian who believes there is a chance he could return to the US PGA Tour and scale the rankings once again.
Woods held golf's top spot for a total of 683 weeks and a record 281 consecutively.
"I'll try and get as close as I can to that number, yes," he said.
"I'm very optimistic (with) how I'm progressing; "I'm still training. I'm getting stronger.
"The pain is gone, but I don't know what my golfing body is going to be like because I haven't hit a golf shot yet.
"I don't know what 100 per cent (healthy) means after eight surgeries and I've been out of the game for a while.
"First things first; get my health organised. Make sure the pain goes away."
Earlier this year Woods was arrested in Jupiter, Florida, on suspicion of DUI but the charges were later dropped.
He has since undergone rehab for an addiction to prescription medication and agreed to enter a diversion program.
