Jonny Wilkinson's mentor Steve Black insists the England fly-half is still four years from his peak and can defy his injuries to play until he is 40.
Black, confidant and personal trainer of Wilkinson, 29, believes he has only reached "about 60%" of his potential.
"I think Jonny is probably going to reach his best when he is 33, 34, from a playing standpoint," Black said.
"Because he has looked after himself so well, I could see him playing on until he is 38, 39, 40," he told BBC 5 Live.
Wilkinson has suffered more than a dozen major injuries since kicking England to World Cup glory in Sydney five years ago.
He is currently sidelined with a dislocated knee, an injury he has described as "the most debilitating I've had", which is likely to keep him on the sidelines until March and out of the 2009 Six Nations.
Wilkinson insists he is "absolutely" confident he will return to top-flight rugby after his latest problem, and admits the prospect of a third Lions tour, to South Africa, next year is a motivation in his rehabilitation.
And Black believes the fitness and form the fly-half showed in the three full games he played for Newcastle this season before his injury at Gloucester on 30 September is evidence he can prolong his career.
"Jonny is cerebral as well as physical," Black explained. "He will continue to get better physically until he is 32, 33.
"When he came back for those three games earlier this season, he was doing remarkably well. He was playing well, his decision-making was very good and physically he was excellent.
"I think he has got so much more to give the world of rugby. We have not seen the best of him by a long way.
"I would think we have seen about 60% of Jonny Wilkinson. I think we are going to see him get better physically and his decision-making will improve even more because he learns from each occasion and all the experiences he has. He will get better and better."
"He's incredibly authoritative; he knows what he wants, and that's a great sign of a guy in a decision-making position"
The Newcastle fly-half, who in September revealed how Buddhism and quantum physics have helped him find a more relaxed approach to life, insists an England return is not the be-all and end-all for him.
"If I'm playing the best I can be, there is nothing else," he told BBC Radio 5 Live. "It's irrelevant if I'm an England player or not.
"I believe if I go about things the right way my future will be just as I need it to continue to get better and better.
"If I wanted to play for England I could maybe get back in there like I did before, I could hang in there for a bit and not really enjoy myself.
"I could squeeze through a few games and spend the end of the week almost sobbing into my pillow and finding a way to get through, not get much sleep and then work towards the next one, finish my career and work out what to do with myself.
"Or I can have a fantastic time, with whichever team I'm with, trying to help them get better, and let the best of me come out, and combine that with where life is going.
"I used to judge my life on titles. I wanted to play for England and win a World Cup. Well I did those things and I wasn't happy. That is the point."
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"Danny's an explosive character who has burst onto the scene with a huge amount of talent, and that talent is ready to come out," Wilkinson added.
"He's played a lot of games for his club and he's done well, playing under seriously high pressure. He's played for England now and he knows what he's doing.
"I've been in the squad when he's been playing and he's incredibly authoritative; he knows what he wants, and that's a great sign of a guy in a decision-making position.
"He knows what he wants to see on the field, and he's learning his way to get that message right on there.
"He is a massive part of it and he's only going to get better."
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