The most improbable, incredible two minutes of Sir Alex Ferguson's five-decade long footballing life began when a goalkeeper went forward 100 yards for a corner. With Peter Schmeichel providing considerable nuisance value in the Bayern Munich penalty area, Teddy Sheringham equalised in the Nou Camp. Soon afterwards, Ole Gunnar Solskjaer pounced for the winner. The rest is history: football, bloody hell and all that.
The last line of defence has occasionally proved a valid form of attack for Manchester United, while midfielders have sometimes been a useful form of defence. But, for the third time in three years, opponents have exploited United midfielders' unfamiliarity with unusual duties.
In December 2009, Michael Carrick and Darren Fletcher were ersatz stoppers as Fulham won 3-0 at Craven Cottage. On Ferguson's 70th birthday, Carrick and Valencia began at the back (and, bizarrely, right-back Rafael da Silva was in midfield) when Blackburn won at Old Trafford. And on Monday, the Ecuadorian and the Englishman were the right half of a defence that Everton bullied.
Poor Carrick is the constant, a willing stand-in who must anticipate an SOS every time the United defence is depleted. Yet simply standing over six feet tall does not make him a central defender. He is a languid playmaker, not the second Steve Bruce. Valencia has spent some of his international career as wing-back, but last season was the Premier League's outstanding out-and-out right-winger. It is waste to drop him deeper.
It is also the product of misfortune. Any club with four sidelined central defenders - as United, minus Rio Ferdinand, Jonny Evans, Phil Jones and Chris Smalling, are - can consider themselves unlucky. The last man standing, Nemanja Vidic, spoke after the setback at Goodison Park and underlined his no-excuses mantra. A can-do mentality and an unbreakable resolve can take a team a long way, as United have proved in the past, but injury crises at the back are almost an annual occurrence.
And their impact is exacerbated by the ever-increasing imbalance in the squad. Even with the addition of Alexander Buttner, Ferguson only has eight actual defenders, and it is hard to view the uncapped Dutchman as anything other than an occasional deputy for the overworked Patrice Evra.
Of those eight defenders, only Jones, Smalling and, at a push, Evans can play both in the middle and on the flank. A year after he joined Sunderland, the unheralded utility defender John O'Shea is missed.
Now consider an attack given an expensive overhaul; £44 million of the £48 million spent has gone on progressive talents. While many a manager wants a host of forward choices, United have 11 senior players capable of occupying the front four positions in their new-look 4-2-3-1/4-2-1-3 system - Valencia, Nani, Tom Cleverley, Ashley Young, Ryan Giggs, Shinji Kagawa, Robin van Persie, Wayne Rooney, Dimitar Berbatov, Javier Hernandez and Danny Welbeck. Of those, only Valencia and Hernandez are only suited to one role (Berbatov used to stroll around behind Robbie Keane at Tottenham) and several could operate in three of them.
Even before factoring in one summer signing, Nick Powell, and another whose arrival is yet to be ratified, Angelo Henriquez, and even without including Federico Macheda and Bebe, Ferguson has myriad options. It could take a season purely to test out every potential combination.
Even among the emerging, the same pattern continues. In Will Keane, Jesse Lingard, Larnell Cole and Davide Petrucci, Ferguson has understudies for his attackers. Only Frederic Veseli and Scott Wootton, an unused substitute at Goodison Park, offer any cover.
United have probably the most prolific academy in England, but many of those who have rolled off the production line have gone. Fabio da Silva is on loan at QPR and Ritchie de Laet, whose progress had stalled, was sold to Leicester. There might be greater regret that James Chester and Joe Dudgeon were allowed to join Hull last year. Both left with the path to the first team blocked.
Chester might have got a game now, but instead Carrick is likely to continue at centre-back against Fulham, removing a cornerstone of the midfield - albeit another department where Ferguson may have too many choices.
Because while circumstances mean that the optimum squad size can vary by the week, its composition involves a greater balance between attack and defence. Especially with such injury-prone centre-backs, United have a shortage of defenders and a surfeit of forwards.
Men like Carrick and Valencia have proved admirably versatile, and while Ferguson can be inventive in his decision-making at the back - he once won a game partly by turning Giggs into an emergency left-back - there is sometimes a need for specialists. It may not be total football, and it certainly wasn't in the cauldron of Goodison Park on Monday night.