The issue was always going to revolve around Sir Alex Ferguson's assertion that he had "boys" he could trust to carry him on the last steps of the road to Moscow.
It was a big leap of faith, considering how United lost their way on the Fulham Road at the weekend, but then maybe the boy he had most in mind came fresh to the night that would shape Manchester United's season.
Maybe the boy was Paul Scholes, who so often finds the best of himself when the stakes are highest. He has, of course, been doing it for a long time now and if his legs feel heavier on some days than others as he pushes into his thirties, there is still never a question mark against his instincts or his nerve.
Last night it was Scholes, and some almost surreal defensive vision from Rio Ferdinand, which kept United alive in the face of the mesmerising facility of Lionel Messi.
Scholes insisted that before the lights of his career go out, he must go to Moscow. Whenever the Argentine prodigy touched the ball, the crowd booed. It wasn't disrespect or displeasure or any accusation of dark intent. It was pure terror, and if it is hard to know how deeply the United players felt the same level of apprehension as Messi bore down on their goal, twisting, biting, and once drawing a fine save from Edwin van der Sar, we could be sure of the value of Scholes' intervention in the 14th minute.
It was a strike from 25 yards, after Gianluca Zambrotta had played the ball off Cristiano Ronaldo's feet into Scholes' path, that did more than bring the Kremlin wall into focus. It broke, for a life-preserving breathing space, the spell of Messi. No one demonstrated the importance of this more than Scholes inside the first minute. Overwhelmed by a combination of speed and guile, Scholes lunged into the tackle. He has never claimed flawlessness in this department of the game and his salvation here was that the crunch came not much more than an inch outside the penalty area.
The implications of a Barça strike on United's psyche were not pretty to contemplate at such an early point of the proceedings and it was as though the entire stadium produced a collective gulp. Messi was that dominant as the focal point of attack in a Barcelona who once again seemed intent on passing United to the verge of a coma. Scholes' strike broke that sense that United were condemned to another night of marking shadows and hoping, against the odds, that something would turn up.
Of course, Scholes turned up with a superb sense of what he had to do. He did it with a beautifully flighted shot that didn't so much lift the pressure as inject new life. Nani twice and quickly had chances to throw Barcelona back on their heels, but each time the chances were missed. It meant that United needed superb defence, especially from Ferdinand and Patrice Evra, who once again was obliged to face down the relentless running and trickery of Messi.
He did it with superb application, if not always with complete success, but as the minutes ticked away the tension so near to a runway to Moscow became so heavy it seemed that United's nerve had never been so stretched, for so long and so desperately, since they won the great trophy against Bayern Munich at Barça's Nou Camp nine years ago.
Messi refused to stop his quest and in stoppage time remained a one-man source of agitation to Ferguson's heart.
Ronaldo? The man whose absence from the vital Premier League challenge at Stamford Bridge caused so much tactical debate, so much questioning of Ferguson's judgement, was in truth not much more than a spectator. If destiny called to him, it found that on this occasion he wasn't at home. However, he lived through the siege of Messi, like all his team-mates,and now he has the chance to decorate his image in the biggest game in club football. George Best, the player with whom the Portuguese is most frequently compared, had a similar opportunity 40 years ago, and he took it with a vital performance.
This is now the obligation on England's footballer of the year. Last night his rival Lionel Messi produced more than 90 minutes of relentless commitment, but he couldn't find the moment that broke United. He threatened it a score of times. He moved with balance and trickery, and if he could have picked up his team and carried it across the line he surely would. But that was beyond him, he did not have the break or the help that at vital moments were so desperately required.
The job went to a man from the other side who had at least one last shot to fire. His name, perhaps not to the total surprise of his manager, was Paul Scholes.
Semi-conscious Manchester United's European Cup semi-finals
Manchester United's match with Barcelona last night completed their 10th semi-final in Europe's premier club competition. Of the previous nine United advanced to the final on just two occasions, once under Matt Busby in 1968 and also under Sir Alex Ferguson in 1999. In both years the Red Devils went on to lift the trophy.
Real Madrid 3 Manchester United 1; Manchester United 2 Real Madrid 2 (lost 5-3 on aggregate)
Manchester United 2 Milan 1; Milan 4 Manchester United 0 (lost 5-2 on aggregate)
Partizan Belgrade 2 Manchester United 0; Manchester United 1 Partizan Belgrade 0 (lost 2-1 on aggregate)
Manchester United 1 Real Madrid 0; Real Madrid 3 Manchester United 3 (won 4-3 on aggregate)
Milan 2 Manchester United 0; Manchester United 1 Milan 0
(lost 2-1 on aggregate)
Borussia Dortmund 1 Manchester United 0; Manchester United 0 Borussia Dortmund 1 (lost 2-0 on aggregate)
Manchester United 1 Juventus 1; Juventus 2 Manchester United 3 (won 4-3 on aggregate)
Manchester United 2 Bayer Leverkusen 2; Bayer Leverkusen 1 Manchester United 1 (drew 3-3 on aggregate; lost on away goals)
Manchester United 3 Milan 2; Milan 3 Manchester United 0 (lost 5-3 on aggregate)