Britain's Nicola Adams became the first woman to win an Olympic boxing title by bullying her way to victory over China's number one seed Ren Cancan, taking the flyweight gold.

Adams easily recorded a 16-7 win in the final at the ExCel arena in south east London as she dominated the three-times world champion from start to finish, recording a rare knock down in the second round.

The Briton shadow boxed in each corner of the ring with delight after her name was read out as the winner following the exciting four two minutes rounds.

"It is a dream come true. I am so happy and overwhelmed with joy right now. I have wanted this all my life and I have done it," a beaming Adams told reporters, who could not believe she scored a knockdown.

"I didn't see that coming, but it happened. I was just thinking of becoming Olympic champion. The feeling is absolutely amazing."

Adams evaded the jabs of Ren to land clever shots and get in the face of her opponent, who had impressed at the Games with her ability to fight at a distance with her rangy jab.

Adams then landed a left followed by a massive right hand halfway through the second round to dump Ren flat on her back on the canvas to give the Briton a 9-4 lead at the bell.

The blow unsettled Ren who tried to mix it with Adams rather than use the boxing artistry that had taken her to her world titles and built her reputation as one of the finest women boxers.

Adams continued to land shots in the third as she ducked her way past Ren's weakening jab to land flurries of punches with both hands to take the third 5-1 and a 14-5 lead.

Ren looked out of ideas in the final round as Adams stayed out of trouble to ease to victory in a country where women could not get a licence to box 15 years ago.

In the middleweight division American teenager Claressa Shields outfoxed and outgunned Russian Nadezda Torlopova to win gold.

Shields took the bout 19-12 at the Excel Arena in east London to claim America's only gold medal in the ring at the Games after the nine men all exited before the semi-finals.

The grinning Shields danced her way out of the arena to cap her rise to the top from the tough streets of Flint, Michigan.

Following a cagey opening round, Shields broke open a big lead after a strong second round where she utilised her quicker hand speed to land a number of scoring blows in the tight exchanges with her bigger opponent.

The Russian, at 33 almost twice the age of her opponent, took more punishment in the third round as Shields landed with a couple of big left straights to take a 15-10 lead.

Shields ducked and dived away from the lumbering blows from the tired Russian, making her miss with ease.

Losing semi-finalists Li Jinzi of China and Kazak Marina Volnova took bronze.