Briefly Hamed's splendid opponent threatened to repay him for all the cringing boastfulness he had been made to undergo throughout the week leading up to the fight. There was, however, no answer to the brutal right uppercut with which the showman from Sheffield ended proceedings slightly more than two minutes into the eighth round. It came all the way from Hamed's ankles and seemed to travel all the way down to Johnson's in return.
The 32-year-old from Indiana, who had 11 times defended the IBF title, fell to his knees and slumped. The referee, Rudy Battle, had no option but to stop it. But Hamed knew by then that he had been in a contest. Paying tribute to Johnson, in contrast to the positive malevolence he had exhibited in previous days, he said: "He's a brilliant fighter with a great chin. I have all the respect for him. There has been nobody who's knocked him down. I said the third round, but he took some very good shots."
He did indeed. While it may not reduce the Prince's swagger it may just make him think twice before disparaging future challengers. Still, the clinical manner of his finish did not make it possible to doubt his off- quoted prediction that he will go up the weights as his career progresses.
Hamed preened as ever. He showed his chin and threw punches from areas as yet unnavigated and smiled. His supporters presumably think this is a winning way, opponents must differ. But Johnson did not budge.
Hamed briefly exploded into action as early as the second round after an exploratory first and in the third he produced an array of punches with both hands that had Johnson on the brink. But it was the American who had the final word in that round with a hard right to the side of the Englishman's face.
It seemed as though Hamed at last realised this was no ordinary challenger, but still he insisted on trying to discover the knock-out blow. Many punches were wasted while Johnson, upright, flowing and correct, did much good work inside with his jab. It was easy to tell that things were not going swimmingly as Hamed's fans went quiet. Was he to make the journey from boxing Prince to boxing pauper?
But in the seventh round Hamed unfolded a right which was followed by a left and from that there was never an appropriate reply. Towards the end of the round he had Johnson all but helpless in his own corner and probably decided which of his marvellous armoury of punches he would bring out to end it soon afterwards.
Hamed was not the only one to have trouble finding his rhythm in London Arena last night. Steve Collins, focused as ever, did not win quite as smoothly as the predictions supposed. There was nevertheless much of that which was typical of the Irishman as he stopped the Frenchman Frederic Seillier in the fifth round, because of a cut eye.
On the front of Collins's shorts is emblazoned his ringed sobriquet "Celtic Warrior". It is an unnecessary addition as he once again demonstrated in retaining his WBO super-middleweight title. He stopped the challenger in the fifth round.
Everything which the stocky, stubborn Irishman does in the ring is focused. His eyes remain on his target, his head is still and although his rhythm against Sellier was never at its most fluent, he was always in control.
Collins has been around too long - 12 years - to let his championship slip easily and jabbed away with his usual determination. He got the decision on a cut to Sellier's left eye which opened in the second round and continued to swell as Collins kept picking it off with long lefts.
There was a Gallic swagger to Sellier but in truth all the arrogance deserved to belong to Collins. He smiled warmly afterwards, something he will never, ever do in the ring and declared once more his intention to fight the IBF champion, Roy Jones. "I will fight him any time, anywhere. I want Jones to come out of hiding."
This may be a deserved bout but it may not be straight forward. There is one Robin Reid to consider now. It took the Liverpudlian with the brooding looks of a matinee idol longer than he might have either expected or wished to retain his World Boxing Council super-middleweight title on the same bill last night. Reid was taken to the seventh round before he delivered the violently decisive right hand to the jaw of the South African Giovanni Pretorius.
Not that there was anything remotely of the lounge lizard in Reid's approach to his first defence of the championship as he came out booming with punches, and in two minutes Pretorius was down under the insistence of the onslaught.
But he worked his way gamely inside just as it looked as though Reid would be able to get home long before the pubs shut. "I took some shots I shouldn't have done. But I proved I am not just a puncher. I reverted to my boxing," Reid said.