In the end, Daniel Dubois made the necessary adjustments and left Fabio Wardley in boxing’s dreaded wasteland on Saturday night at the O2.

All the talk before the opening bell of their heavyweight rematch was about the changes that Wardley needed to make to get revenge for his bruising loss in 11 rounds just five months ago.

Dubois listened patiently during a week of confrontations, held his tongue as Wardley and his team outlined the essential adjustments required. Wardley, having dropped Dubois twice in the early phases of their first fight, promised to manage the rematch better and finish Dubois quicker if the latter was hurt. Dubois just sat, mostly in silence.

The first bell sounded, and Dubois was transformed, cutting down every inch of Wardley’s ring space and, inside 20 seconds, connecting with the best right cross of his life to drop Wardley for the first time in his career. The fight was essentially over then; Wardley never recovered.

The official ending came after 2:21 of the second round, but Wardley only made it that far because of his heart and bravery. He was never in the fight, not for one second. He stayed on his feet, but he was repeatedly trapped on the ropes or in a corner and was hit with just about every single punch that Dubois measured and threw. It was clinical.

Dubois, as was revealed by his trainer Don Charles, had warmed up for longer and started his fight preparation earlier; in the first bout, in May, Dubois was dropped in the opening 10 seconds and again in round three. Dubois has been dropped four times in the opening round of fights.

On Saturday, he reversed the process and simply never gave Wardley a chance. It was an obvious tactic, but Dubois pulled it off with power, accuracy, speed and belief. Wardley was stunned, retreated in a hurry and never had a moment to show what he had prepared.

In the fluid inquest at ringside and online, in the fight’s sudden aftermath, there was a lot of bold talk that Wardley had taken the rematch too soon after the brutal first fight. The simple truth is that Dubois – working behind fast feet, a ramrod jab and an accurate right cross – made all chatter redundant.

Wardley was taken out because he was simply not good enough, and not because he was beaten five months ago and was feeling the effects of that night.

There is no exact science in the boxing business for getting a beaten fighter back in the ring, no guidebook to help trainers; a boxer knows and a trainer knows if the man is ready to get back in the ring. The opposite of that would mean that both a boxer and his trainer are risking the life of the man by accepting a fight too soon. Ben Davison, Wardley’s trainer, is not a butcher, and Wardley is not a fool – they were ready for the fight, just not ready for the Dubois that came out of the opposite corner.

Dubois is now firmly established as the No 1 active heavyweight in the world, a position that should always be based on recent performances not history, and he holds the WBO belt; the three other champions are in his slipstream.

Frank Warren has a promotional deal with three of the four champions – Dubois, Filip Hrgovic and Agit Kabayel – and has promised unifications next year, with Hrgovic facing off with old opponent Dubois late on Saturday. Warren has also promised a new undisputed champion at some point. Wardley is now in a chasing pack but still has options.

The Daniel Dubois from Saturday’s brief encounter would have dropped any heavyweight at any time in history, and he sent a chilling message to the veterans and the contenders in the current division.