Andy Murray may never again have an imperative quite so weighty as the one that sits on his shoulders when he walks on to Centre Court today. He has to create one of the great convulsions in Wimbledon history by beating the magnificent Rafa Nadal.
He has to define precisely who and what he thinks he is – a young man born to be a great champion or someone who might never quite get his sometimes troubled head around such an uplifting idea.
He has to play not just with the brilliance that has been increasingly evident these last few days but the conviction that, at 24, this is his time, his moment, and that if it passes him by it may never come again, at least not on quite the same tide of encouragement.
Can he do it? Yes. Will he do it? Yes, if he can create for himself optimum circumstances of self-belief.
This means that he must not only put faith in his natural ability to play tennis sublimely enough to trouble any opponent, including the relentless Nadal, anywhere and at any time, but also see clearly the possibility of becoming the first British champion in 75 years as not so much a challenge as a birthright.
For so long it seems that Murray has struggled to grasp quite how good he is. Introspection of an often bleak kind can descend upon him as quickly as a hawk swooping on a victim.
Twice he has, however harsh it sounds, betrayed himself at the highest level of the game.
Here two years ago he allowed the feisty but much less talented Andy Roddick to have his own belligerent way. In Melbourne at the start of this year he was not only eviscerated in the final of the Australian Open by Novak Djokovic but so badly traumatised some feared he might be broken for ever.
Yet almost all the recent evidence says that the wounds are healed and that his impressive play on the clay of Paris and his flamboyant victory at Queen's really did speak of a new Murray, a more seasoned, tougher character less susceptible to the controlled competitive fury of Nadal.
Yes, it is still a huge reach even when you have retraced Murray's impressive march into the second week of the tournament, his brisk and authoritative dismissal of the potentially dangerous French maverick Richard Gasquet and the dismemberment of the beautiful but excessively elevated quarter-finalist Feliciano Lopez.
Neither victory was likely even to graze the confidence of the reigning champion Nadal but Murray's court time was the chance to reveal rather more than a mere hint of new composure.
That doesn't automatically put any more mustard on his second serve – a weakness that some hard judges believe Nadal will exploit cruelly – but it might just say that if the champion is to win, and brush aside the fear that the cortisone treatment he is now receiving before every match is not a guarantee against a further eruption of his injury, he may well have to do it without the help of his opponent.
It certainly cannot harm Murray's psyche that at least two former Wimbledon champions are prepared to go public with their belief that this may indeed be the moment when the boy from Dunblane with the wispy facial hair becomes a fully grown competitor of the most enviable talent.
Boris Becker seized his breakthrough moment at Centre Court when he was still just 17 years old, an achievement somewhat psychologically detached from Murray's goal today at a more advanced age. However, if there is one witness with impeccable credentials to assess Murray's situation, it is surely the man who won in 1996, the 6ft 5in hard-hitting Richard Krajicek.
The Dutchman was just a few months older than Murray is today when he created a sensation at Wimbledon which the Scot can only rival, not surpass, if he brings down the two-time champion Nadal. Krajicek knocked out Pete Sampras – who had won three straight titles before going down in the quarter-final – and went on to take the crown with a three-set defeat of the lightly regarded American MaliVai Washington.
As dusk came to Wimbledon on Wednesday, Krajicek insisted that this indeed could be the moment when Murray rearranges the tennis order.
"It is so much harder today because back when I beat Sampras a Grand Slam tournament could suddenly open up if the big player lost. Now, when Federer goes down, we still have Nadal and Djokovic and Murray – and who can say, if Tsonga plays something similar to the way he did to beat Federer, that he cannot go on to win the title? This is truly a great age of tennis, it is incredible, but, yes, I do believe Andy Murray has his best chance.
"I was worried for him after he lost to Djokovic in Melbourne. It was a bad defeat and it seemed to have a terrible effect on him. But then we saw him play so well in Paris and he looked very good, very happy at Queen's.
"I still felt that he would probably have to win another Grand Slam title before he could do it here because of all the pressure he faces. But I no longer believe he cannot win Wimbledon this time. In the last few days he has convinced me he can do it. I'm not saying he will, you cannot be sure about that when you consider the players still here. Yes, it is also true he faces Nadal and we have known for some time how awesome he is. But Murray does have the game to win, he has every shot you would want. He just has to remember to play them all. If he does, Nadal could have a real problem."
Krajicek certainly remembered his own assets when he faced Sampras and shaped the great upset – a killing serve and a carefully reconstructed backhand. At 39 the Dutchman is still proud of that booming service game, reporting that in the doubles company of 2001 winner Goran Ivanisevic this week it went in on at least one occasion at around 130mph. Though his Wimbledon triumph was his only Grand Slam title, Sampras regaining his hold on Centre Court in four more finals, Krajicek produced perfectly, the achievement demanded of Murray today.
He beat Sampras in straight sets, 7-5, 7-6, 6-4, delivering the great American's only defeat in eight years of Wimbledon action, and compiled a 6-4 winning record against the man who for so long squeezed the life out of all opposition.
Today Krajicek appears improbably fit – "I may look ready to play but I'm not – not against those guys," he says with a smile when two female fans leap out of the gloaming – and is conspicuously relaxed. He runs the Rotterdam tournament, writes books and works for young people in the inner cities, for which he was given the Arthur Ashe Humanitarian Award. He doesn't say it in quite so many words but some of his contentment may still flow from the day he won the greatest of his victories on a tennis court.
He can always tell himself that there was a time, a handful of vital moments, when he used every single one of his assets – and it was a day that will always make him proud.
It may be helpful to Andy Murray that Krajicek wants him to know that a similar gift could be in his possession before the end of today.