Tiger Woods will never reach the form that saw him win 14 golf majors, according to Australian legend Greg Norman.
Woods has suffered a string of injury problems, last playing a PGA tournament in August last year.
The 40-year-old has had three operations on his back in 19 months and recently delayed his comeback after withdrawing from the Safeway Open.
"The older he gets, the younger the other players get. It's harder for him," Norman told TMZ.
"Quite honestly, to compete at that high-end level - you're body doesn't allow you to do it.
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"Your mind wants to, but at the end of the day, it's very difficult to match these kids who are in their twenties when you're in your forties."
It has been eight years since Woods last won one of the sport's four majors, with victory in the 2008 US Open.
Woods said last week he was aiming for a December comeback and had not given up hope of eclipsing Jack Nicklaus' record of 18 major championships.
Norman urged Woods to be realistic about his prospects.
"At the end of the day, you've just got to look at your options, be a realist to yourself," he said.
Woods has admitted he could no longer "do the things I used to", telling CBS he needed to "find different ways to go about it".
