Two of the most accomplished and respected managers in Premier League history might just have thrown their title chances out the transfer window.

Now Sir Alex Ferguson and Arsene Wenger have time and time again proved that their plans and decisions are invariably above and beyond what we mere mortals can fathom, but at the moment it seems they have both handed the initiative in the title race to Chelsea by screwing up during the January transfer window.

Whether Arsene Wenger should have bought a striker in January is no longer up for discussion. It’s a fact that he messed up there – he has the money, he has players waiting to sign up to play for him, and he certainly knows the players he wants to play for him – big mistake, no excuses.

After last weekend, it was Sir Alex Ferguson’s turn to have his managerial skills questioned.

 As United reject Louis Saha effortlessly tore into the fragile Wes Brown-Jonny Evans during Everton’s recent 3-1 victory over United, the suggestions that Fergie should have acquired defensive reinforcements in January suddenly seemed like common sense.

The Brown-Evans combination had already endured a torrid game against a Ronaldinho-inspired AC Milan several days earlier, and would have been under severe scrutiny had Milan not been so wasteful in front of goal during the first 15 minutes when Evans in particular looked to have his Jean-Alain Boumsong boots on.

Jonny Evans: Still too young to shoulder United's defensive responsibilities?

And last month’s United-Arsenal match kind of embodied the mistakes both managers made during the transfer window. Brown was being turned inside out by Andrei Arshavin, but Arsenal could not profit from it as they didn’t have a goal-scorer to finish off the Russian’s fine work.

And as 18-year-old Jack Rodwell sped past the lumbering, heavy-legged Evans to power home Everton’s third goal, the point was nailed home – Fergie should have bought a defender.

As with Wenger, Ferguson has his reasons. While Wenger’s is an unflinching and often frustrating commitment to preserving financial sustainability, which more often than not feels like an excuse for him to stick with his stubbornly purist approach to developing footballing teams, Ferguson’s was more practical – there were no options.

He said: “If someone could give me the name of a really good centre-half who would accept a three-month contract then I would jump at the chance, but where do you find a player like that?

“A decent player would be looking for a three-year contract and I don’t need that kind of addition. It’s already difficult enough leaving good players out of the team without adding another to the mix.”

And that is where Ferguson is seriously mistaken – he does need an addition at the back for the next three years.

Sir Alex doesn't believe his team needs any long-term additions in defence.

Apart from Ferdinand and Vidic, United only have the inexperienced Evans as a specialist centre-back. Brown has shown himself to be a much better right-back over the last few seasons, and is now a stand-in centreback at best. They need another experienced, quality defender comfortable in the heart of defence.

A centre-back who can also play on the left would certainly be useful considering how Patrice Evra has been so overworked in the past few weeks, and John O’Shea might be out for the rest of the season.

Moreover, of all people, you’d expect Ferguson to put winning the Championship ahead of keeping a couple of fringe defenders happy with enough game time.

But whatever his reasoning, the damage has been done.

Against Everton, United lacked the solid defensive base from which they could launch their potent counter attacks, and the nervousness at the back spread throughout the entire team, allowing Everton to take control of the game.

Equally poor defending allowed AC Milan back into a tie which United were lucky to have taken control of. The goal they conceded to make it 3-2 could well prove costly in the second leg.

Fergie’s faith in Evans was obviously misplaced. The young Ulsterman certainly has the potential, but United’s recent successful league campaigns have been built on a solid foundation of defensive brilliance, which have allowed their talented attackers the confidence to pour forward.

United haven’t changed the way they played this season, which places a great deal of pressure on Evans, something which Fergie obviously thought he was ready for, and was obviously wrong.

In simpler terms, just as Arshavin declared that Arsenal would not win the title if he continued playing centre-forward, United cannot win the title with Brown and Evans at the heart of defense.

Even without Ferdinand’s four-match suspension for lashing out at Hull City’s Chris Fagan – which Fergie had plenty of time to take into consideration since the Hull game was over a week before deadline day – it would have taken Rio at least a few games to get match fitness, and god knows what kind of stupid tricks he does when he’s not fully fit.

Many would say money was a factor, but then why did Fergie splash eight million pounds on Chris Smalling?

Wenger’s mistake in failing to bring in a striker has already been viewed as fatal to their chances of winning the title this season, and possibly of keeping Cesc Fabregas at the club.

Sadly, Ferguson seems to have made a similar mistake, though arguably in a more understandable situation.

But the way this season has gone, we’ll never know. Maybe the two will defy the critics to once again prove why they are the greatest managers ever in the Premier League.