CELTIC MAY have scaled the heights to record back-to-back SPL title wins in the past two seasons but they can no longer truthfully claim to be head and shoulders above their nearest challengers. Not only did Rangers' comprehensive 3-0 victory over their Old Firm rivals at Ibrox last week bring the champions down to earth with a bump, it may yet prove to be an epoch-defining moment in the evolution of the modern Scottish footballer.

This theory of history sees the battle for supremacy in the Scottish league less as a series of random events and more of a continual struggle by competing managers to exploit the perceived weaknesses of their nearest challengers. In the recent history of Scottish football, this almost always occurs between one side of Glasgow and the other.

First in this broad-brush analysis comes Martin O'Neill, whose answer to the cash-rich hegemony of Dick Advocaat at Ibrox was to buy tall, physically-imposing players such as Chris Sutton and Bobo Balde, mould them into a unit, and frequently bypass the midfield altogether. Alex McLeish could hardly fail to notice this successes - the two Scottish cup final goals even in defeat in May 2003 by Balde and John Hartson are thought to have been particularly helpful in jogging his memory - and before long he too started to fill his side with giant doppelgangers such as Sotirios Kyrgiakos, Marvin Andrews and Dado Prso. Sick of being physically bullied, supposedly second-tier sides such as Hearts, then more recently Dundee United, have had their own success by following the same trend.

Yet if Strachan's contribution in his two successful years to date has largely been to get the ball down again and re-introduce the winger, last Saturday may just go down as the point where this process was adjudged to have gone too far too soon. Rangers started the match with more than half an inch height advantage over Celtic, and although none of their goals - other than a penalty - came directly from a set piece, the Ibrox club made the most of the physical mismatch in their appetite for 50/50 challenges. Celtic were quite simply strongarmed out of the game.

Having had his own glorious playing career despite his 5ft 6in frame, it must pain Strachan to make such adjustments, but even during the crushing late midweek defeat to Benfica, the relegation of Scott McDonald (5ft 8in) and Shunsuke Nakamura (5ft 10in) to the bench in preference to Chris Killen (6ft) and Jiri Jarosik (6ft 4in) appeared to be at least partially motivated by an attempt to ensure his side were competitive in both penalty areas.

Having said that, leaving your dead-ball specialist on the bench hardly increases your chances of scoring from a set piece.

"Set pieces are absolutely huge," Strachan said, "and there are taller people playing now. When I was playing in Scotland, everybody had two centre halves who were tall, and the rest of us were all between five foot and six foot. If you look at Dundee United, Rangers and Hearts now they are all huge and you have to have a certain amount of players who can head the ball away or you will suffer.

"I went to see Dundee United versus Motherwell the other week, and there was absolutely nothing in the game. Then all of a sudden there was a corner kick, the boy at the far post wins a header and the game's finished. The difference is that the ball moves quicker, they can get more swerve on it, so you need to be able to protect different areas."

Strachan insisted that such facets of the game were "not really a source of concern" but with Walter Smith's Rangers side having won all three of the battles between the teams - by increasing scorelines of 1-0, 2-0, 3 - and three potentially-season defining Old Firm games to go, not all of the club's supporters would necessarily agree with him.

"They won more challenges than us in the middle of the park," Strachan recalled. "You don't have to be a giant, but you have to be clever sometimes, and be brave.

"I was watching Aussie Rules: if you can't win that bit in the middle, then you can't go and play elsewhere. Even in rugby, if you don't win the ball in the ruck then you can't go and play elsewhere. Football - I will show you any result; take my team, I have got every stat you could possibly want, that if you lose out on the tackles then you lose out in the game. We outpassed Rangers by 120 passes, we had 14 attempts on goal to their 10, we had possession longer than them, but it all comes down to where you win the tackle and how quickly you move it on from there."

Yet even after two such demoralising outcomes in the space of seven days, Strachan still has plenty to feel positive about. His side went into the weekend still top of the league, and two home wins will still gives them a decent shot of Champions League progression.

Not that he has time to dwell on things anyway. After yesterday's meeting with Motherwell, there is the visit of Hearts on CiS Cup duty on Wednesday night, and the club are already "out there looking at some positions" ahead of the transfer window opening in January.

"At the moment we have taken a couple of knocks in terms of both mental and physical knocks and you just get on with it," he said. "How do you get back to feeling positive? I just need to look at this group of players. When it is fully fit, I think it will be good. I look at where we want to add to that group. And yes, I am positive. I can't help it, that is how I feel." Strachan, rest assured, still has some big ideas.