In Dublin this weekend two men who are friends, who have both managed Celtic, and who could hardly be any different as football managers, will lock horns in the Aviva Stadium.

Martin O'Neill and Gordon Strachan forever speak fondly of each other, in part due to their shared experience in Glasgow's east end. Being a Celtic manager binds together the men who have walked in the footsteps of Jock Stein.

O'Neill did it for five years and still talks about it to this day. Strachan did it for four years and called it "one of the greatest experiences of my life". Whenever Strachan and O'Neill meet socially - which is less so these days - the subject of Celtic soon surfaces in their conversation.

And yet, as mutually respecting and empathetic as the two men are, how different they are, also. O'Neill and Strachan are chalk and cheese as managers, and have proved in the febrile football setting of Glasgow that there is no one right way to do it.

O'Neill was lauded as Celtic manager - adored you might call it - and is now replicating his direct, muscles-showing football with the Republic of Ireland.

Packie Bonner, a legend of Celtic and Ireland, spoke this week about O'Neill's "sometimes route-one, high intensity game" with his national team. Of course, such blunt descriptions never quite do anything justice, but the point is well made and accurate.

O'Neill had Henrik Larsson at Celtic, a goal-scoring machine, and his first thought was to get the ball to Larsson as quickly and directly as possible.

When Larsson left Celtic in 2004 the team was suddenly left with two target men, Chris Sutton and John Hartson, in attack. The scenario might have made other managers pause for thought, or even adjustment.

Not Martin O'Neill. He was delighted by the prospect. He could hardly wait to see Sutton and Hartson mowing down anything that crossed their path.

One of the first things Strachan did when he arrived as Celtic manager in the summer of 2005 was sign that delicate little bird, Shunsuke Nakamura.

The Japansese playmaker became a hit with the Celtic support, not least for that spear of a free-kick he despatched past Edwin van der Sar in Manchester United's goal in the Champions League at Celtic Park in November 2006.

In all seriousness…can anyone imagine O'Neill giving even five seconds of thought to signing a Nakamura? The midfielder was everything - lithe, light, butterfly-like with the ball - that makes O'Neill come out in a cold sweat.

The Celtic support feasted on the O'Neill years, but it was more about the glory, and the doings doled out to Rangers, than the aesthetics.

Strachan, just as he is now doing with Scotland, set Celtic on a different road. Nakamura's arrival from Reggina was the first abrupt sign of it. The Celtic of 2005-08 was quite different from the O'Neill years previously.

O'Neill gets regularly brassed-off by some of this talk - he thinks the summations of his football with Celtic, Sunderland and Ireland are crude and make for caricature. But he shouldn't do.

Football is about the winning - and O'Neill did plenty of that with Celtic. In March 2003 Gerard Houllier's Liverpool fussed about with the ball, being prissy, being artistic, while O'Neill's Celtic got on with putting their opponents to the sword.

That was a memorable Anfield night for O'Neill and Celtic. Winning is fine, it's great fun. There is nothing wrong with it at all.

O'Neill shouldn't care if some football writers suddenly turn into ballet critics when they are assessing what is before them on the pitch. Do most fans care? Do they really concern themselves with "style" more than the winning? Of course not.

These days, their club feats now behind them, there is one further theme that binds O'Neill and Strachan - they are working, not without exception, with some moderate talents.

It is taking O'Neill all his guile and know-how to wring goals out of this Ireland team. Three times so far in group D - against Georgia, Germany and Poland - the have scored at the death to redeem themselves. O'Neill must somehow make something out of his Daryl Murphy straw.

Just so with Scotland. When Colin Jackson died this week, it was a reminder of the fine centre-backs Scotland once produced with relative abundance. Jackson won only eight caps in his 18-year career, but what Strachan would do for him today.

The Scotland manager has grafting central defenders at this level - no more than that - to choose from. Like O'Neill, he has to improvise, to delve deep into his football wisdom to make it work.

They are fascinating characters, O'Neill and Strachan: two different football managers, thrown together once more in a shared experience.