THIS report starts at the end, because that was when terms such as “global superstar” were being cast around with unchallenged abandon. Best performance by a British boxer? Best of all time, came the counter-argument.

While this was all going on, Joe Calzaghe was bounding puppy-like to all four corners of the ring, ecstatically acknowledging the crowd who were ecstatically responding to him. Champion boxers invariably salute their victories in this way, but here was mutual recognition that the late night winner had taken far more than just another scalp.

In not one of the 12 rounds he had just contested and won so comprehensively did he pause for air or let his phenomenal workrate drop, yet here in its aftermath, the fatigue of his extraordinary performance slipped from him. Calzaghe was now the supreme king of the super-middleweight division, yet titles and belts were merely the dressing for an entirely new status.

This is not hyperbole, this was the real thing. One of the great nights, a masterclass and an American at the wrong end of it leaving his title and his fearsome reputation behind him in the ring. Until those early hours of yesterday morning, Jeff Lacy was unbeaten and stood tall as one of the great hopes for the future of American boxing. The Showtime network had billed the 28-year-old as its coming man, the star of its stable. “I’d have bet my house this fight would not look like that,” Gary Shaw, Lacy’s promoter, said. “Obviously, I’d have lost my house.”

And for all their self-belief, not even Calzaghe’s corner can genuinely have envisaged this fight looking like that. Certainly, the crowd could not and we must go back to 2 o’clock yesterday morning for that. In the long wait for the culmination of Calzaghe’s career, we had to camp out until the early hours for American television to switch on.

By this stage, the inside of the MEN Arena had started to resemble an airline departure lounge with a clientele waiting for a flight that, rather like Calzaghe’s career, has had its take-off repeatedly postponed. The drunk and the dishevelled lay sprawled across rows of seats while the hardcore maintained the pace in the bar. All were putting in the hours to find out whether Calzaghe could really get off the ground, but there was no tingle of expectation, no sense that this was a man who could really fly.

The cliché called this his “defining fight”. The anomaly was that Calzaghe is 33 years old, was 8½ years the WBO champion, unbeaten throughout his entire professional career and yet still a boxer who lacked definition. Maybe the least recognised champion in the British Isles — across any sport perhaps? That’s subjective territory, though the same can never be said again.

That much was clear from the first round. Calzaghe defined himself as a pugilist in those first three minutes. He started like a sprinter, with a staggering speed from the blocks that surprised opponent and audience alike. He was so fast, he simply thudded such dazzling, accurate combinations of punches into Lacy’s face that the American could barely fire a shot.

When they broke at the bell and Calzaghe finally paused for breath, the first drops of blood had started to trickle from Lacy’s nose; he looked bewildered, outclassed. The bout, as a contest, may not have been over at that stage but it was already pertinent to question how Calzaghe could possibly lose.

The only answer was probably Lacy’s left hook, a weapon that does not come well disguised. Calling yourself “Left Hook Lacy” is a bit of a give-away, though on this occasion the most we saw of it was on the stitching on the back of the American’s tunic. Lacy did swing enthusiastically, but did not connect. The same could not be said of Calzaghe, whose accuracy was unremitting.

It was as early as the second round that Calzaghe saw the cul-de-sac down which he was driving his infuriated opponent. With a minute to go, he peppered Lacy’s face with another flurry of punches and then leant back and leered. This was uncharacteristic for a boxer whose decency does not stoop to showboating — it was more a recognition of how much he was enjoying the ride.

By the third round, the crowd had recognised it too and were chanting “Easy!” By the end of the fourth, Lacy had streams of blood running down his face and in the fifth, the soundtrack of “Easy!” was reprised along with the staccato beat of left-right, left-right into Lacy’s features. By the sixth, Lacy’s staying power was becoming as remarkable as Calzaghe’s talent and in the seventh, the Welshman started looking for the finish.

He would never get it. He delivered 12 rounds of exhibition boxing, the fast, accurate combinations continuing to the very end. He did not lose a round, indeed, he barely lost a second, and the fact that Lacy was knocked down only once was testament to an extraordinary display of physical courage. Enzo Calzaghe, father and trainer of the victor, said that had he been in the opposite corner, he would have been thinking about pulling Lacy out as early as the eighth.

Enzo also told us about the injury to the left wrist that his son suffered three weeks ago. He snagged it in training and was 50-50 over whether to withdraw from the bout altogether. That Calzaghe came through that, with the help of five days off and a cortisone injection, says something in itelf, though Frank Warren, his promoter, got it spot on when he told him that if he did not go through with the bout, his chance may be gone for good. Now that we have seen how magnificently he took it, it is astonishing to reflect that the real Calzaghe may never have taken off. All those years he has been in the departure lounge; now he flies as high as any of them.