Yesterday they finally unfurled the roof over Centre Court and in so doing, they discovered a brave new world of suffering for the British public. Beneath its folds, Andy Murray was put to an extreme test of five sets of intermittently brilliant and constantly nerve-jangling tennis. At times superb, at other times tantalising us with errors, Murray had his credentials for this and every other grand-slam tournament examined with forensic care.

Stanislas Wawrinka came into the match with the thoroughly laudable desire to prove that there is more than one decent tennis player in Switzerland, and he has certainly succeeded in this ambition. Murray was asked to go slumming into the most secret and sordid parts of himself. It was a test of tennis skills, but above all, it was a test of fighting spirit.

Wawrinka has a fair amount of that himself, but in the end, Murray had what mattered at the brutal sharp end of a protracted match, finally winning 2-6, 6-3, 6-3, 5-7, 6-3. You can make your own conclusion here. It was either a display of weakness or a display of inner strength; it was either the stuff of a next-round loser or the stuff of champions.

Yesterday, Murray had a serious lesson in being the target, in being a marked man - a new experience for him at this level of competition. Wawrinka asked a series of deep and searching questions as the sky darkened over SW19, but play continued beneath the Centre Court roof and the lights glowed out through the gloom.

Wawrinka proceeded to throw all his best stuff at Murray - and Murray was totally knocked off his stride. Gone in the space of a few points were the serenity and self-certainty he showed us in the past couple of matches here. Wawrinka came out like a train - really pinged his lid, as dog-racing people say. Yes, really got an early sight of the hare. He knew exactly how to do damage to Murray, attacking the fault-line of the second serve. Murray's second serve has a fair bit of spin and kick on the ball, but no pace whatever. Touch of the Françoise Durr, really: it can dip below 80mph, and that's nothing.

So it was a somewhat eerie start to proceedings. The roof gives a strange acoustic to the place. It sounded more like the Water Cube in Beijing than Centre Court as we know it. Shouted remarks echoed around the arena, the light was unearthly - like something out of Close Encounters of the Third Kind - and instead of the pin-drop silence before the serve, the true sound of Centre Court, there was the background grumble of the air conditioning, as if a dragon were breathing somewhere down in the cellarage.

Wawrinka reeled off the first four games of the match - the sound of ball on racket emulating a shooting range - and helped himself to Murray's second serve like a photographer at a press buffet. You have a real problem when your opponent is gormandising on your second serve: it doesn't half put the pressure on you to get the first serve in. So much pressure that you start missing it. Which gives your opponent more second serves to feast on.

That is precisely what happened: Wawrinka adopted the right tactic, and carried it out with courage and certainty. Murray was absolutely blown away, made to look a second-rater. He was learning what it was like to be an Aunt Sally. With Rafael Nadal out, it was against Murray, with his added burden of being the crowd favourite, that the lesser lights wished to excel. It was against him that they looked for their best tennis. Wawrinka certainly found his.

His thundering rolled backhand had Murray staggering; his touch and court craft had Murray rocking. So this, then, was where we were to find out a great deal more about Murray's competitive nature than we knew before.

It was there before us to examine, as if on a petri dish, in the eighth game of the second set, when, at last, Murray forced the match to a tipping-point, finally drawing the error he needed from Wawrinka to break. Cranking himself up to a frightening level of intensity, bellowing, roaring, double-fisting at the crowd in acknowledgement of their support and a plea for more, smiting himself on the forehead after any errors, he took the second set to a standing ovation.

Wawrinka failed to do the decent thing and fold. Murray was forced to earn every point. Yet Murray has that champion's ability of being unembarrassed by his own difficulties, of always concentrating on the fight. A champion must be happy to get down and dirty if he has to and Murray did exactly that. He saved three break points in a tumultuous game in the third set, and in the next game broke Wawrinka before going on, unstoppably, to win the set.

Still Wawrinka declined to give up, hammering the ball back at Murray, doing everything he could to make life difficult for him, mad with the joy of competition. It was a wonderful fight, sustained for an astonishing length of time, and it told us more about both men than we expected to learn.

Murray did everything to raise the level of his game in the climactic set against a man who simply refused to lie down. It doesn't make him a champion, but it is the sort of thing that champions do.