Sometimes in football, as in life, it is necessary to resort to your gut. You have to understand that it is your head that is going to be on the block - and that if it is not going to be tossed in the basket you may have to follow your deepest instincts.
Maybe we should remember this in the knowledge that any kind of final judgement on those of Liverpool manager Brendan Rodgers will no doubt be hugely influenced by what happens at Anfield tomorrow.
Then, we can be sure a black or white verdict will follow his fielding of a radically altered team in Madrid. Equally certain is that defeat by Chelsea will call into question not only one bold or, if you prefer, crazy set of selection decisions but almost everything he has done since Luis Suarez inevitably took flight.
But then this is the luxury of the army of critics who include most vociferously Gary Lineker, the multi-millionaire television face who when asked if he had ever contemplated taking on the challenge of football management snapped, "You must be joking."
It wasn't for him, Lineker sniffed. He decided that while watching the likes of Alex Ferguson and Arsene Wenger torturing themselves on the touch-line.
Now it is Rodgers fighting to achieve career momentum but if he stops Chelsea, if his desperately under-performing key players show that sitting on the bench in the great theatre of the Bernabeu has indeed concentrated their minds, Rodgers might be excused a claim of superior psychology.
Certainly he would have emerged from one of the tightest corners of his brief, hugely promising but currently embattled career. He would have been seen to have taken his fate into his own hands, decided that the time had passed when he could comfortably predict that his team was about to turn a corner.
At this point only one thing can be said with any kind of certainty. It is that Rodgers made his call knowing that it would be received with much scorn by those appalled by the idea of a five-time European champion running up the white flag in the great Spanish bastion of football tradition. He could have written the headlines himself.
Still, he did it. He chose to make himself the lonely man in the tumultuous stadium. He braved the jeers of Liverpool supporters and the derision of Real. He may have noticed the baleful expressions of his captain Steven Gerrard and Raheem Sterling, Jordan Henderson and Mario Balotelli (no change, here, though) as they sat on the bench, and if he had later called for translations he would have read reviews that ripped into his integrity.
Most damning was the verdict of Mundo Deportivo, which trumpeted, "Dismissing the Bernabeu in such a way is not the behaviour of a distinguished manager." For Rodgers the reality is that he will carry such an insult lightly if his team come out mentally re-fitted against Chelsea, if they show that they finally realise that not only one season but whole careers are currently in the balance.
Another truth, whatever the consequences at Anfield, is that Rodgers was not dismissing the Champions League in Madrid. Demonstrably, he was seeking an impact not on the terraces of the Bernabeu housing fans who had seen their team demolish a "full-strength" Liverpool at Anfield but the minds and hearts of a squad which had fallen so far below an adequate level of performance a few days earlier at Newcastle. And a team which all season has been straining, and failing, to match the rhythm that was so thrilling before the late season meltdowns against Crystal Palace and Chelsea which wiped out an often breath-taking title challenge.
Rodgers clearly reckoned that he had to do more than mouth the platitudes which had been accumulating at the same rate as doubts about Liverpool's ability to find meaningful life after Suarez. He had to make his players look at themselves in a more searching way and when he left the Bernabeu he could reasonably claim that his players had indeed had their noses pushed against the fact that what they had been doing, was nowhere near to being good enough. He didn't throw away Liverpool's hard-won legacy, he didn't throw a game in world club football's most prestigious tournament. He said that it was time for players to stand up to be counted. He had carried the great weight of the pressure quite long enough.
Whichever way you look at it there was certainly no easy sense of players like Gerrard and Sterling enjoying a night-off from the trenches. Their faces were as taut and anxious as their manager's. Perhaps, who knows, they have received the kind of call to arms which is becoming increasingly required down the road at Manchester City.
There are some obvious parallels. City flounder in the vacuum left by the departure of Yaya Toure's most uplifting form and authority. Indeed, Toure's red card in this week's disaster against CSKA Moscow seemed like the last word in a story of dwindling commitment. He came into the season against a background of widespread doubt about his continuing dedication to the City cause. Now almost every performance reeks of a failure of sustained will. He unfurled a brilliant free kick against CSKA - but only after going missing at a free kick when City fell a goal behind.
Gerrard came into his season under the shadow of his calamitous slip against Chelsea but not short, apparently, of a bullish belief that he could indeed have another run at a Last Hurrah in the title race and a return to Europe. The available evidence has not been convincing, a fact conceded by his old colleague and friend Jamie Carragher when he suggested that Gerrard's younger team-mates should do some of his running. Nor was confidence hugely enhanced when Gerrard discussed his future beyond next season and revealed that Liverpool had not made any move to renew his contract. That, in all the circumstances, was something Rodgers would have preferred to leave in a back corridor of Anfield.
As it is, at least the manager is out in the open with his concerns about the progress of his team. They showed, he said, an improvement in resolve, a deeper determination in his players to find the best of themselves.
City manager Manuel Pellegrini could only dream of such speculation after his team's abject surrender.
Astonishingly for a team which has won two Premier League titles in the last three years, they remain a monument to under-performance. Pellegrini winces and talks about inhabiting a difficult moment when really, he is trapped in a culture of wealth and self-regard without any embrace of ultimate responsibility. The honesty and brilliance of such as Sergio Arguero and David Silva seems to shine in ever increasing isolation. So what does Pellegrini do?
For the moment, no doubt he will, along with the rest of English football, examine the action at Anfield to see if his young rival has earned any reward for what might prove not an act of folly but some basic and timely courage.
I know that feeling when a career in professional football is reaching its latter stages. When the legs ache more than they should in a warm-up, when it seems like a young lad in training has got the measure of you, when you jog on to the pitch and find yourself asking that same question: what am I doing here?