IT can be a dangerous game to write off Scott Brown, and I would know.

Like many others, I felt that the Celtic captain should have taken the opportunity of early semi-retirement a couple of years back and play out the rest of his career in the sunshine of Australia when the opportunity presented itself. He wasn't quite ready to be put out to pasture, but his hamstring problems and other fitness issues at the time led more than a few commentators and supporters to surmise that his best days were behind him.

Instead, he signed a new Celtic contract, got stuck right back into the blood and thunder of Scottish football, and emerged with renewed vigour and a couple of Trebles to his name.

And fair play to him for that. Brown deserves huge credit for the way he roared back under Brendan Rodgers, and then continued to be the standard bearer for the rest of the Celtic squad under Neil Lennon.

The start of this season though has seen some of those old questions about Brown's place at the heart of the Celtic midfield arise once more. At 35 years of age now, there are those who are doubting whether the unquestionable influence that Brown has on those around him is enough to outweigh the supposed deficiencies that have crept into his game due to his advancing years.

Indeed, my own colleague James Cairney produced a reasoned critique of Brown on this very back page last week, suggesting his lack of attacking output and diminishing defensive contribution so far this term, albeit from a very limited sample size of just four Premiership matches, meant that it was time for Brown to be phased out of Lennon's starting XI.

Indeed, the succession plan for Brown's place not only on the field, but off it, is undoubtedly on the minds of the Celtic staff. Callum McGregor seems to have been groomed for the role, and although a vastly different character in terms of demeanour, he is already exhibiting the leadership qualities in a playing capacity and around the dressing room that mark him out as the obvious candidate to assume the position once Brown finally hangs up his boots.

At the risk of sparking a roll-around in the Herald office with my esteemed colleague Mr Cairney though, I believe that moment is still some way off.

One of the many privileges of being among the only people allowed into stadiums to actually watch football in the flesh, and one of the only upsides to having no supporters there alongside you, is that you get to hear what the players are saying to each other.

It is perhaps no surprise that at Celtic matches, one voice is louder than all the others.

Brown joked after Celtic's win at Tannadice that he can't wait for crowds to come back so that his cajoling of teammates would once again be drowned out, but it has offered a fascinating insight into just how influential Brown is on those around him.

It isn't just the clichéd "Get into them from the first minute" and "We've not started here lads" stuff that you can hear on any Sunday League pitch either, although he does a fair line in that too. But oftentimes he is issuing specific instructions - either tactical or an edict to remove a finger from a certain orifice - to individual teammates too.

That mixture of constructive criticism and rough and ready motivation makes him an invaluable asset to Celtic, even in matches where he himself may not be playing all that well. But for me, the perception of the waning of his contribution in a footballing sense is also being overblown.

Yes, Brown is no longer contributing much in an attacking sense, but that hasn't been in his job description for years. I would fancy that his defensive stats though, which have admittedly dipped a little at the start of this term, will soon return to the levels that marked him out as one of the best deep-lying midfielders in the Premiership last season.

When Brown was absent from the side through injury a year or so ago, there was a strong case that the partnership between McGregor and Olivier Ntcham at the base of midfield allowed the ball to be moved forward quicker than it had been, and therefore made Celtic's wingers far more effective as a result.

There is sound reasoning behind that theory, but there was little surprise that as soon as Brown was fit again, he was straight back into the side.

It is hard to argue against that decision given the success that followed, even if the quandary of accommodating the hugely talented Ntcham in the side and keeping him happy is one that the Celtic manager must also wrestle with. With David Turnbull now also in the squad, that balancing act becomes harder as Lennon's options increase.

Elsewhere in these pages though, Brown has insisted that he feels 21 again. If anyone on the fringes is looking to gatecrash the starting XI this season on a regular basis, it would be a brave man who would count on it being at the expense of Brown. Having been burned once, that man won't be me.