Professional boxing operates on a simple principle: destroy all harmony. It has been that way for a couple of centuries and it is not altogether a mystery given it is a sport that accommodates raw, if legal, violence.

That it is why casual observers were pleasantly surprised when Anthony Joshua and Wladimir Klitschko refused to “get in the gutter” before trying to knock each other unconscious in front of 90,000 fans at Wembley two weekends ago.

There is another world title fight of some consequence in London on Saturday night, between two unbeaten and talented young boxers that should need no extraneous noise, a contest that is capable of carrying the freight on its own. And, despite hardwired instincts to lower the tone, it has largely stayed within the new AJ-Wlad parameters of good manners.

Gervonta “Tank” Davis, of Baltimore, who makes the first defence of his super-featherweight WBO title against the No1 contender, Liam Walsh of Cromer, at the Copper Box Arena, has a street history to suggest he is suited to overblown trash-talking and he did his best. “I’m just on a whole different level,” he said. “I do know they built you good but you’ve been dropped before. They’ve been protecting you from the power, so I know you have no chin. On Saturday night you’ll be on your ass.”

By the trade’s standards that is mild stuff – as was Walsh’s response: “I applaud him. Tank is the best fighter I’ve come up against in my career so far but I’m also the best fighter he’s going to come against in his career so far. You won’t see me celebrating like a mad man if I knock out Tank because I know I’m capable of it.” So, milkshakes all round.

What hype there has been has centred not so much on the fledgling champion, who is being hailed as the “next big thing” in a sport that is always looking for TNBT, and he might yet turn out to be just that. Nor have Walsh’s Farmy Army from Norfolk gone over the top. The reason the fight is causing a stir is that Davis – who took three attempts to make the weight on Friday – is being pushed by Floyd Mayweather Jr. And what 22-year-old champion who has risen from nothing would not want the endorsement of a semi-retired multimillionaire legend who describes his protege as “the future of boxing”? It has seemed during the long run-up to the fight that Mayweather is the real star of the show. He has been his mercurial self, refusing to confirm if he will fight the MMA loud-hailer Conor McGregor, and instead has trained his verbal guns on Walsh. Although he revealed he has been out of the gym for a while, he reckons he could beat Walsh and his two boxing brothers on the same night. Now that would sell tickets in Norwich.

A clue as to how boxing as a sport has been almost irretrievably turned into showbiz, however, can be found in an article on boxing in the sports pages of the New York Times on Friday, 620 words long – and not one of them devoted to their American champion and his first world title defence.

There is, however, detailed examination of the likelihood or otherwise of Mayweather fighting McGregor, who has not boxed since he was 15 but who is rather good at mixed martial arts and self-promotion. Towards the end of an article devoted not even to the core boxing art but to the peripheral excitement it generates, the author observes of Mayweather, “As a draw, he has transcended the floundering sport in a way that few, if any, boxers have in recent years.”

It is difficult to argue with that when the participants themselves play the game. Mayweather is a master of the wind-up, in the ring and outside it, an egotist who delivers on his boasts, or did until he retired unbeaten after 49 bouts.

He will be at the microphone on Saturday. BoxNation and Showtime will hang on his every word. Mayweather’s man might well be too strong over the distance for Walsh but he will not have it his own way in every round.