The 20-year-old's score of 76.483 points saw her finish ahead of compatriot and three-time world champion Yana Kudryavtseva and Ukraine's Ganna Rizatdinova, the silver and bronze medallists with 75.608 and 73.583 respectively.

Russia have won every gold medal in the sport since Sydney 2000 and Mamun succeeds Yulia Barsukova, Alina Kabayeva and Evgenia Kanaeva as the fourth consecutive gymnast from the country to claim the Olympic title.

She turned in four scores over 19 points in the final to hold off the challenge of Kudryavtseva, her friend and rival.

"It was quite unexpected for me to win the gold medal because all of the competitions like today, Yana Kudryavtseva used to win," Mamun said.

"That's why I wasn't thinking about winning the gold medal.

"It just happened that way."

Kudryavtseva, 18, came to Rio 2016 as the favourite for the title and led at the halfway point of the competition as expected. 

She made a fatal mistake at the end of her clubs routine, however, when she missed a catch.

It was her only error of the night, but it was enough to put her out of contention for gold.

"It all happened very quickly and I didn't manage to quickly find a way to solve the mistake," said Kudryavtseva.

"That's why I lost the club.

"I've been competing for 13 years, so of course this has happened before.

"Sometimes at the end of my routines, I'm too relaxed and I think I already have an apparatus in my hand when I don't.

"That is what happened today."

Mamun saved her best for last, delivering her highest score of the competition with the ribbon, 19.233 points, to seal the gold.

The first to greet her as she came off the floor was her coach Amina Zaripova, who 20 years ago finished fourth in this competition at the Olympic Games in Atlanta.

Rizatdinova won a three-way battle for bronze with South Korea’s Son Yeon-jae and Belarus’ Melitina Staniouta just missing out. 

The two-time world medallist's third-place finish comes four years after a disappointing 10th at London 2012.  

Son, fifth in London, moved up a place in the ranking to secure a best-ever finish for a South Korean gymnast at the Olympics. 

As the 2015 world bronze medallist, Staniouta began the afternoon as a potential podium contender, but after two mistakes with the clubs, she had to settle for fifth.

In group all-around qualification, Spain finished ahead of four-time champions Russia and could win their first Olympic gold since 1996 if they match their performance in tomorrow’s final.