BOXING:THE KATIE Taylor firestorm blew hard through the London docklands on Thursday. All that remained yesterday were the embers, a few old papers blowing around the kilometre-long mall that houses the boxing arena and the madness of almost 10,000 Irish fans. Then John Joe Nevin arrived.

Nevin did the almost impossible, recharged the Irish campaign and illuminated the Olympic tournament only hours after Katie had drawn the last vapours of energy from this week’s snowballing boxing carnival.

The bantamweight from Mullingar, who had to be coaxed to come to London, has been taken by Billy Walsh and Zaur Antia and converted from a beaten docket low on self-belief into the architect of one of the great Olympic boxing performances.

It has been a stunning transformation.

Watching Nevin’s 19-14 quarterfinal win over Cuba’s Lazaro Estrada Alvarez, it was a performance both mesmerising and ferocious. His balletic movement ranged from the slow sway of a keening woman to a flashing red shirt and a blur of stinging blows. The Cuban world champion was at times reduced to swinging at a target that was and then wasn’t there.

Nevin’s extraordinary reflexes, balance and self-belief reduced his opponent to a gawking onlooker in a breath-taking Olympic semi-final.

“I just believed I could beat the best in the world,” said Nevin.

He now faces Britain’s third-seeded Luke Campbell for the bantamweight gold medal this evening in what could be a repeat of Taylor’s high octane meeting with Natasha Jonas earlier this week.

Nevin’s joy also came within 30 minutes of Paddy Barnes losing to world champion Shiming Zou.

Walsh was seen running through the arena to get to Nevin, his disappointment for Barnes masked and suppressed as Nevin prepared to go in against Alvarez.

“The difference in emotions within half an hour of each other, it’s crazy stuff,” said Walsh.

“It was doom and gloom and then you’ve got to change your face for him [Nevin] and be up for him and get him ready, and make him believe that he can deliver.”

Nevin delivered from the off in a bout in which Alvarez wanted to fight but Nevin was never going to. With his movement and his hit-and-run style, the Irish boxer is proving to be one of the most elusive in the world.

Scoring with his quick flicking hands, Nevin glided and hit, then disappeared. The speed of his left and backhand was instantly a problem for the world champion and Nevin led 5-3 coming out of the first three minutes. But he was just warming to the challenge.

He began the second round by cracking in a right hand the moment the two came out. Alvarez went chasing more aggressively and while both fighters were scoring Nevin kept his tempo and patience.

He won the second 7-6 to bring his score to a comfortable 12-9.

Finally Nevin began beating the Cuban to the punch and at times almost nonchalantly scored with whipped, accurate shots. It was comfortable enough to showboat in the third round, his self-belief now soaring facing into Britain’s Luke Campbell in the Olympic final.

The Yorkshireman, who has Irish grandparents, beat Nevin in last year’s World championships in Baku in a 12-12 countback fight. But Campbell later lost 14-10 to Alvarez in the final. “I’ve got Irish family and they know his family – simple as that,” said Campbell.

At 5ft 11in (1.8m), the Hull fighter is unusually tall for his weight division but an added bonus to the gold medal is the winner will be the first non-Cuban fighter to win the bantamweight title in six Olympic Games.

“Hopefully, I’ll go and perform now the next day and let the best man win on the day,” said Nevin. “I can beat anyone on the day and I can lose to anyone on the day if I don’t perform. That’s the attitude I’ve taken from the start. Go in, do my best and come out smiling. I’m just going one step at a time, one minute at a time, one round at a time.”

Walsh was also buzzing at the level of performance.

“Yes. He was a world champion and he made him look ordinary. He played with him. He even did the Mullingar Shuffle, you know what I mean?” said Walsh.

“He knows he’s going to improve. His sharpness in training and between fights is electric. As he says, he’s enjoying it and that’s making him so good, and there’s no pressure on him. He’s going in there and he’ll probably be against the favourite because he’s a British boy, a hometown boy.

“If it’s good enough . . . he will be good enough . . .” After yesterday that is not in doubt.