Zheng was seeded second day after a super second-half of the 2015 season in which she had claimed gold medals at the Summer Universiade in Gwanju and in World Taekwondo Federation Grand Prix legs in Manchester and Mexico City.

She also took an under 73kg silver medal at the World Championships in Chelyabinsk in May, but had never won a world or Olympic title at senior level.

That all changed today, however, as she cruised through the earlier rounds before a superb semi-final victory over Britain's world over 73kg champion Bianka Walkden. 

Mexico's Beijing 2008 gold medal winner Maria Espinoza stood in her way in the final but proved unable to cope with the relentless power and precision of the Chinese star.

Zheng opened the scoring in round one with a body kick before countering twice for third round strikes in a 5-1 victory.

It ensured China's third heavyweight gold medal in the sport, following the trail blazed by Sydney 2000 and Athens 2004 winner Chen Zhong.

"I am taller so I tried to keep my distance," said a delighted Zheng.

"If she is close she is faster than me, so I kept her away.

"I feel very happy and excited."

Espinoza completed a full set of Olympic medals after adding silver to her Beijing 2008 gold and London 2012 bronze.

Walkden recovered to take Britain's third taekwondo medal of the week by sharing the bronze medal with United States' Jackie Galloway.

Taekwondo has proved a superb opportunity for new countries to find a place on the medals podium and it happened again in the men's over 80kg competition when Niger's Issoufou Alfaga Abdoulrazak secured a spot in the final.

He was up against Radik Isaev, a Azerbaijan fighter who switched nationality from Russia in 2012.

After a scoreless opening, Isaev broke through in the scond with a head kick before a securing a second three-pointer in round three for a 6-2 victory.

It marked Azerbaijan's first gold medal of Rio 2016 after four silver and 10 bronze.

"We waited long for this medal and we all worked hard for it," said the 26-year-old, who claimed World Championship and European Games under 87kg titles last year.

"We did it and took the gold!"

It still marked the best ever Olympic performance for Niger, whose only other Olympic medal was a bronze for light welterweight boxer Issaka Daborg at Munich 1972.

Brazil claimed its first ever male taekwondo Olympic medal when Maicon Siqueira delighted the home crowd with bronze.

He shared the final spot on the podium with Cha Dongmin of South Korea.