While it is absurdly easy to look at the state of the defences currently playing for Arsenal and Manchester United and compare them unfavourably to the robustness of old, let us not forget that even in their heyday, when they were the two best teams in the country, they suffered some unfortunate implosions.

In 2001, Sir Alex Ferguson’s reigning champions lacerated Wenger’s side 6-1, with Dwight Yorke enjoying one of those golden afternoons when the ball seemed entranced by his presence. The Arsenal rearguard that day included Oleg Luzhny, Gilles Grimandi and Igors Stepanovs (Nelson Vivas came on in the second half), perhaps not their most stellar lineup, which just goes to prove that a cluster of simultaneous injuries can play havoc even with teams that are generally well constructed.

Later that year, the Arsenal team that would seize the upper hand and claim the Premier League title embarrassed United with a 3-1 victory at Highbury, helped by two bizarre gifts from Fabien Barthez, who yanked at his own shorts in frustration as he presented Thierry Henry with a pair of assists.

So lopsided do these teams both appear to be in their current incarnations – with their overloaded firepower and wafer-thin back lines – defensive apprehension from Arsène Wenger and Louis van Gaal is understandable before their meeting on Saturday evening.

Some years ago, Lee Dixon – a full-back by name and nature – was thrown on as an emergency centre-half in the latter stages of a game against Newcastle United, which required the daunting task of marking Alan Shearer. “I was like a fish up a tree,” he says, chuckling at the memory. He has some sympathy with Nacho Monreal, who has been moved to the middle on a semi-permanent basis and is clearly finding the experience an ordeal.

It has been particularly difficult for Arsenal and Manchester United to find any defensive rhythm this season because of the constant juggling due to injuries. It is no coincidence that Chelsea and Southampton are the Premier League pacesetters:they have used only two variations in their back lines for Premier League matches all season. Arsenal have used six variations; United eight.

“It’s massively unhelpful,” adds Dixon. “I have watched Man United a few times and I couldn’t write a Man United back four down. I played in a back four that changed very rarely and you could almost mind-read what is going on to the side of you or slightly behind you. You know the player, what he is thinking, what position he might take.

“I knew where Martin Keown or Tony Adams would be. You get an inner sense of where they would be on the pitch. When you have got that going on it doesn’t half save you a lot of running, looking over your shoulder, indecision about where you should be. That’s a massive factor.

“It’s what’s going on in front of the back four too. Teams are more cavalier. I don’t care how good a defender you are, if you are outnumbered it is a lot more difficult to defend than if you have numbers on your side.”

Dixon reckons it is “dangerous ground” to fall into the trap of a defenders-were-better-in-my-day critique, even though it is an easy conclusion to draw. It is, he reckons, more about the quality of defensive coaching and team organisation rather than the quality of the defenders themselves. “There is a seemingly more attack-minded philosophy by managers now,” he says. “With attacking full-backs the back line is broken up more than perhaps it has ever been. It’s great to watch but there are big mistakes all over the place. The game is not coached as it used to be.”

The manner of Arsenal frittering away a lead in their last couple of matches alarmed Dixon. Not only for the individual errors (with Laurent Koscielny and Mathieu Debuchy sorely missed the pressure is intense on Calum Chambers and Monreal) but more pertinently for the way the team did not appear to have a clue about helping out team-mates who were under the cosh. United had a similar experience when they let in five at Leicester City in September.

“That is the more worrying side of what is going on in football,” Dixon says. “There doesn’t seem to be an awareness of what is going wrong on the pitch. It’s fine looking at the sidelines and blaming managers – ultimately the blame falls to coaches as they are supposed to coach players to know the gameplan.

“If I was getting a bit of a roasting, a word would come from somewhere. Somebody on that pitch would have said to me: ‘Dicko, stay tight on him for five minutes. Forget about covering us lot, we will sort that out. We are going to stop that problem.’ As defenders you are putting fires out all over the pitch. You work out where the problems are and you solve it yourself. Yes, the manager has an input but when there is an obvious thing going wrong, you can get through it.

“I am telling you the messages that come across from the sidelines are borderline gibberish – it’s Chinese whispers by the time it comes across the pitch and has probably turned into something else. You can get messages on the pitch but in general you find out at half-time the true meaning of what has been said. You have to be able to solve things.

“That comes from training. That has to come from knowing what you are doing in a given situation on the training pitch. You have to work on all aspects of the game on a daily basis but in my opinion defending is more important to work at because you are reacting to different problems. At the other end of the pitch there’s a lot of instinct, off the cuff stuff, you are using your imagination to work things out. At the back you have to be more regimented in what you do.”

The injury problems have highlighted the broader mistake in terms of squad building for the campaign. United had a particularly tough task given the summer exodus of leaders in the shape of Rio Ferdinand, Nemanja Vidic and Patrice Evra.

Van Gaal at least appeared to be trying in terms of defensive recruitment, although Wenger’s neglect of this particular area is arguably the biggest brick his critics can throw at him at the moment.

Is it just too difficult to find Premier League-ready defenders on the open market? Dixon is not so sure. “When we were all bought we weren’t ready. We just went in and worked our bollocks off in training. Defenders just don’t grow on trees.”