Joe Cordina became Wales' 13th world champion as he stunned champion Kenichi Ogawa with a second-round knockout to take the IBF super-featherweight title.
Cordina becomes world champion in just his 15th fight as a professional after he produced the punch of a lifetime.
Cordina's huge right hook floored the champion who was unable to rise as Cordina won a world title in the most dramatic of circumstances.
"I am on top of the world," Cordina declared after his sensational victory.
A narrow favourite against a champion with real pedigree, the manner of Cordina's victory will send shockwaves through the super-featherweight division as he produced a thunderous shot to show he is unquestionably comfortable at a world level.
Cordina, a decorated amateur, has seen his opportunities limited in recent years by a hand injury that required surgery and threatened his career.
- Relive how Cordina knocked out Ogawa as it happened
Undefeated in 14 professional fights since his debut in 2017, Cordina was boxing in his home city for the first time in four years as he bid to join Wales' illustrious list of a dozen world champions.
In front of half of that list - Joe Calzaghe, Enzo Maccarinelli, Robbie Regan, Lee Selby, Gavin Rees and Barry Jones were all ringside - Cordina produced a performance to make any Welsh fight fan proud.
Home advantage decisiveJoe Cordina: What does a new world champion do after his big night?
Cordina, who grew up in the Cardiff suburbs of St Mellons and supports Cardiff City, was enjoying home advantage for only the fourth time in pro ranks, having last boxed in the Welsh capital four years ago at the Ice Arena.
This was an altogether bigger proposition, with a capacity crowd of 4,000 at the Motorpoint Arena, with Cordina personally selling over 1,000 tickets as he looked to fulfil his career ambition in front of friends, family and well-wishers.
Wales has not crowned a new world champion since Lee Selby in 2015 and Cordina faced a tough proposition to succeed where the likes of Jay Harris, Liam Williams and Andrew Selby have fallen short in recent years.
Defeated only once, Ogawa represented Cordina's toughest test as a professional, though he was boxing outside of Tokyo for only the third time in his 29th professional contest.
The atmosphere was crackling in Cardiff and Cordina looked every inch a star as he came to the ring serenaded by a capacity crowd belting out Delilah by Tom Jones.
Ogawa promised to come forward and look to be aggressive in the early exchanges, but it was Cordina who did the damage with an incredible shot that sent Ogawa crashing to the canvas.
Ogawa tried in vain to rise and Cordina's win sparked wild celebrations in front of a raucous Welsh crowd.Joe Cordina becomes Wales' first world champion since Lee Selby in 2015
Injuries overcome as Cordina fulfils destiny
Cordina said in the lead-up to the fight a chance to contest for a world title in his home city is "all he could ask for" as he bid to join the pantheon of the greats.
His path to the top could have been smoother since his professional debut, with a badly broken hand threatening his career and leaving him unable to spar, just like Calzaghe.
However, after a completely fallow 2020 following surgery that saw bone from Cordina's hip grafted to his hand, Cordina impressed in three comeback fights in 2021 as he picked up victories against Faroukh Kourbanov, Joshuah Hernandez and Miko Khatchatryan.
However, Ogawa was a tougher test on paper, only to be blown away by Cordina's thunderous right hook.
"It is a lifetime of work gone into five and a half minutes of work. I'm just so thankful," Cordina said.
"I've been throwing some big punches in this camp, I've been in with the likes of Conor Benn and sparred with him and he is one of the most explosive boxers. We've been working hard in the gym.
"We've been working on that punch all camp and it's an amazing feeling when you put hours and hours into it and it comes off in the fight and it's lights out."
Cordina could make his first title defence against Zelfa Barrett, who won in the bill's main support fight, as he beat Faroukh Kourbanov by a wide and unanimous points decision to take the European super-featherweight title.
BBC Sport Wales understands Cordina could be set for a first defence in September, with Shavkat Rakhimov the mandatory IBF challenger a possible opponent.
Shakur Stevenson, the undefeated WBO and WBC super-featherweight champion, also expressed interest in a future fight with Cordina in a social media post.
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