If Manchester United's comebacks are a tradition, the formation for many a fightback is old-fashioned. The system Sir Alex Ferguson is most associated with is 4-4-2 or, he would argue with reference to split strikers, 4-4-1-1. But when United need goals and have nothing to lose, it becomes 4-2-4, the shape Brazil brought to prominence in the 1958 World Cup.
It is a risky formation but when United have to gamble, they push both wingers right up against the opposition defence, with both full-backs advancing in their slipstream. It can leave the two centre-backs isolated and the two central midfielders outnumbered - and as United's pair usually aren't tacklers by trade, it means they effectively only have two defenders.
But after going 2-0 down to Tottenham, they almost snatched a point playing 4-2-4. After conceding two early goals to Braga, they won 3-2 with a mid-match switch to four up front. And against Aston Villa, there were similarities, both in the scoreline and in the way Wayne Rooney spent the second half playing off the left flank after a substitution.
Succeeding with 4-2-4 depends on confidence, tempo and momentum. If opponents are pushed back by waves of United attacks, it can tire them out, meaning Ferguson's undermanned defence is less likely to be exposed than most. While Javier Hernandez sprung Villa's offside trap for his first goal, when Paul Scholes floated a pass over the back four the home side spent much of the second half camped on the edge of their penalty box. To use the old cliché: attack is the best form of defence.
The deciding goal came from a free-kick but it showed the merit of attacking substitutions even at dead-ball situations. Hernandez eluded Enda Stevens to head in Robin van Persie's free kick. Until his half-time introduction, the Irishman had been shadowing Ashley Young at set-pieces. Hernandez and Young are the same height, but the Mexican is more of a penalty-box predator.
If Paul Lambert could be faulted, it was for failing to react to United's positive changes. But the Villa manager's selections had worked, just as his tactics suggested he had put in plenty of thought. Defensively, Villa tended to drop off, to construct two banks of four in front of Brad Guzan's goal. But there was one exception: Stephen Ireland played as the most advanced central midfielder. When United had the ball, he had one of three options: to close down Michael Carrick, shut off Scholes or position himself between the two to prevent them passing to one another.
He usually opted for the latter, which was a qualified success. One chance, for Christian Benteke, came when Ireland dispossessed Scholes and he made several interceptions from the 37-year-old's passes - the most telling at the start of the move for Villa's second goal - but, with his team-mates retreating, he could not stop United having the ball. Between them, Carrick, Scholes and the veteran's replacement Tom Cleverley attempted 264 passes, completing 90% of them. Unfortunately for Villa, Ireland was on the wrong side of Scholes and the two holding midfielders were backing off when he released Hernandez for United's first goal.
Villa's was a shape that called for defensive discipline from two players who are essentially strikers: Gabriel Agbonlahor, picked on the left wing, and Andreas Weimann, chosen on the right. In their previous two league games, United had successfully isolated a left-back - Chelsea's Ashley Cole and Arsenal's Andre Santos - because their respective wingers did not track back. The issue for Villa was not the conscientiousness of their left-sided pair of Stevens and Agbonlahor, who both worked hard, as much as their competence.
Antonio Valencia and Rafael had the beating of them, sending in 22 crosses between them. One from the Brazilian led to the equaliser, on a rare occasion when Agbonlahor had lost him. But the sheer volume of crosses shows that United focused on their right side, with Scholes sending a series of diagonal balls towards the touchline.
Perhaps it was because the inexperienced Stevens was making his first league start, perhaps simply Scholes' recognition that the partnership of the two South Americans constitutes one of the stronger sections of the United team. Either way, it illustrated that a winger and full-back operating in tandem is not necessarily enough to stop their United counterparts.
The other - and probably preferable - part of the Villa wingers' job description was to break from deep and turn 4-4-1-1 into 4-2-1-3. Meanwhile, Ireland served as the fulcrum of the team, playing passes for the overlapping wingers as Villa looked to catch United on the counter-attack. Because Carrick and Scholes are essentially constructive rather than destructive players, even though both are deep-lying, Ireland was often free to serve as Villa's outlet. Their second goal was a case in point, with Ireland feeding Agbonlahor, whose cut-back was converted by Weimann. Both showed the advantages of playing a centre-forward on the wing, as the Austrian cut infield to score.
The first, also from a left-wing cross, showed the other area where Lambert looked to attack United. While Ireland found space between the lines, Benteke went behind the visitors' back four. Villa were using their back two to operate either side of the United centre-backs.
With a 2-0 lead, Villa's tactics were working perfectly. What Lambert perhaps could have done to preserve the lead was to make his defensive changes earlier. The Scot had showed his positive intent in his pre-match decisions and his eventual substitutions - Brett Holman for Weimann, Karim El Ahmadi for Ireland and Fabian Delph for Barry Bannan - all resulted in a less attacking player taking the field. Arguably each move could have been made sooner. But as Weimann almost got a third goal from a Bannan cross, Lambert was almost rewarded for his faith in his starters. And many another manager has failed to stop a United comeback in the past.