RIO DE JANEIRO (Reuters) - As Simone Biles stood locked in a tight embrace with her team-mate Aly Raisman, waiting for her final score to come up on the big screen, the concerned look in her eyes suggested she had no idea who would be crowned Olympic all around champion.

The American, however, was the only one still in the dark in the brightly lit Rio Olympic Arena on Thursday as the hollering cheers and standing ovation that greeted her final tumbling pass on the floor exercise confirmed what everyone knew long before the judges' verdict came up - Biles was the new champion.

When a stupendous score of 15.933 confirmed she had beaten Raisman by 2.100 points, the coronation that had been in the planning stages ever since she won the first of a record three successive world titles in 2013 could finally take place.

Then the woman who had remained stoic throughout the previous two hours as she showcased her jaw-dropping skills across four apparatus, finally let her guard down and burst into tears.

As the realisation hit home that she finally owned the biggest individual prize in the sport, the crowd saluted a gymnast who had just become the first woman in 20 years to win the Olympic all-around title as the reigning world champion.

Raisman claimed silver with a total of 60.098, while Russia's Aliya Mustafina settled for bronze.

Biles earned 15.866 on the vault, 14.966 on the asymmetric bars and 15.433 on the balance beam - a routine that included her spinning around 900 degrees on the four-inch wide apparatus as she balanced her entire body weight on her right toes.

On the floor, her explosive tumbling passes - which included her trademark soaring double layout with half twist at the end - had the Brazilian crowd on their feet as her sassy moves were choreographed to hip-swinging Samba beats.

Biles' triumph made her the fourth successive American to win the title - following the successes of Carly Patterson, Nastia Liukin and Gabby Douglas - which is the longest winning streak by a country in the Olympic discipline.

Biles and Raisman completed a one-two finish for the second time for the U.S. after Nastia Liukin and Shawn Johnson won gold and silver respectively in 2008.

It was also the first time since 1992 that the both the men's and women's all around champions were members of the gold medal team at the same Olympics.