On Wednesday, during the men’s quarter final, the umpire on court number one was moved to ask those in attendance to concentrate on what was going on in front of their eyes.
Andy Murray was playing Fernando Verdasco on Centre Court at that exact moment, and the noises coming over the side of the court from the denizens of Murray Mound were causing endless distraction.
Those in court one were trying to interpret from the grunts and yelps how the main man was doing. Did that ooh mean he his serve had been broken? Was that aah good news?
Every so often, between games, an update on the score would flash up on the scoreboard. It only added to the sense of being in the wrong place at the wrong time. And when the crowd had seen that Murray was in trouble, they heard a great cheer of approval from over on the hill and they could not help themselves. In the middle of a rally on their own court, they let out a huge collective cheer of their own.
It was the first known occasion that a cheer had provoked a cheer. Which moved the umpire to suggest – out of respect to the participants actually trying to reach the furthest either of them ever have at a Grand Slam - maybe they should just keep their minds on what was unfolding in front of them.
And in truth there was plenty to watch. As he dismembered the game of his fellow Pole, Lukasz Kubot, Jerzy Janowicz announced himself as a real talent.
Never mind what was going on over the road in Centre Court, when you see the speedometer reveal that one of the young man’s serves had been timed at 140mph, you sit up and take notice. Certainly the line judge and ballboy, who were obliged to take rapid evasive action as the serve hurtled past them to thud into the back boards, will not forget that shot in a hurry.
You suspect there will be plenty of that to come in his semi-final. Janowicz can serve all right. It is not just the speed of the thing that is so impressive. It is the geometry. He had his compatriot stretching continuously in this match, barely able to follow the rich variation in trajectory.
Janowicz is not a man without self-belief. He already regards himself as the best player in the world. Modesty is not a concept which much troubles him. And there is every chance that, at 22, he might one day become the world number one. Though he has much to learn before he gets there.
Not least from his opponent in the semi-finals, Murray. Take the difference in the way Janowicz marked victory and Murray’s post-match demeanour. On sealing his straight-sets win over his compatriot, the Pole removed his shirt and whirled it above his head. He punched the air, he spread his arms, he celebrated as if he had scored the winner for Legia Warsaw in the Champions League final.
Then, in a television interview as he left court, he burst into tears of joy. He was much the same in the press conference, almost delirious with happiness, his chest heaving with the emotion of it all.
It was lovely to watch his enthusiasm. Understandable too, given the scale of his youthful achievement. Murray, on the other hand, was entirely monosyllabic in his press duties. He showed not a flicker of excitement. His reaction was as if reaching his fifth successive Wimbledon semi was mere routine, something he did every day of his life.
There was a reason for his behaviour which extends way beyond any wearisome libel about his lack of character. Murray has learned that emotions drain the body of energy. The court is the only place to expose them. Otherwise, keep a check, keep restrained, don’t waste a drop.
It is something Janowicz will come to realise as he accumulates appearances in the latter stages of Grand Slams: don’t let your emotions run away with you. It can be costly.
And it is that gap in experience that is likely to tell in this encounter. Murray will have had his team study Janowicz’s serve. They will have brought in someone with a similar style to serve him up practice shots (as they did before the quarter-final when Greg Rusedski reminded him how to face a left-hander like Verdasco). He will be prepared, studied, ready. And calm.
Janowicz, in contrast, will be an adrenalin-fuelled enthusiast, bounding through his first big fixture like a Labrador puppy (albeit a Labrador puppy with a cannonball serve). Adrenalin is one of the most useful chemical assets a player can turn to legally. It can be enormously profitable. But its effect can also quickly evaporate, leaving the player drained and spent.
That is the sort of issue that Murray long since learned how to resolve. Janowicz’s time will come. But the way the two semi-finalists are going about their business ahead of their match, you suspect it will come only when he has logged this one down as experience.