Gold medallist Brazil's Hebert Sousa celebrates on the podium during the medal ceremony for the men's middle (69-75kg) boxing final bout during the Tokyo 2020 Olympic Games at the Kokugikan Arena in Tokyo on Aug 7, 2021. (LUIS ROBAYO / POOL / AFP)

TOKYO - Unheralded Brazilian Hebert Sousa won the Olympic middleweight boxing gold on Saturday with a stunning third-round knockout of Ukrainian Oleksandr Khyzhniak, turning around a fight he had all but lost to win Brazil's second-ever Games gold in the sport.

Britain's Galal Yafai and Bulgaria's Stoyka Zhelyazkova Krasteva won first boxing golds for their countries at the Tokyo Olympics after dominant displays in their flyweight finals

Khyzhniak had the edge in the fight with quick and big punches but Sousa, who has no championship titles to his name, fought hard to stay in the match and from nowhere unleashed a fierce left that sent his opponent to the floor.

Sousa immediately burst into wild celebration, falling to his knees and screaming out into the arena as a shaken Khyzhniak got back on his feet, staggering, and demanded the fight continue as the Brazilian team rejoiced.

Britain's Galal Yafai and Bulgaria's Stoyka Zhelyazkova Krasteva won first boxing golds for their countries at the Tokyo Olympics after dominant displays in their flyweight finals.

Reigning Commonwealth champion Yafai won on a split decision against Filipino Carlo Paalam in the men's match but was always the stronger boxer, fighting on the front foot and beating Paalam with accurate punches and a composed performance.

Yafai sent the 23-year-old Filipino to the canvas in the first round with a fierce left hook to the chin but Paalam recovered quickly and fought hard for what could have been the Philippines' first-ever Olympic boxing gold medal.

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The Briton, who has two brothers who were professional boxers, kept his cool as Paalam came out battling in the next two rounds, mixing roundhouses with uppercuts through the middle, but Yafai held a strong guard to fend off his opponent.

His gold put Britain second in the boxing medals table behind powerhouse Cuba.

"I'm just so determined to win," said Yafai, a Rio Olympian who quit his job in a car factory to focus on fighting.

"I've just got the heart and desire to win and that worked for me."

A two-times bantamweight runner-up in world championships, 35-year-old Krasteva finally got her gold, showing her experience across the three rounds to deny Buse Naz Cakiroglu, 10 years her junior, Turkey's first-ever boxing Olympic title.

Cakiroglu trailed after the first round and switched tactics in the second, moving from front foot to back foot to try to reverse the advantage but Krasteva stayed strong.

Krasteva, who fought in the 2012 London Games, came out of retirement in 2018 to try to finish her career with an Olympic medal and walked around the arena celebrating, holding aloft her national flag.