American Claressa Shields, a 17-year-old with a megawatt smile, won gold in the 75-kilogram competition with a show of raw strength and aggression against her older Russian rival, Nadezda Torlopova, 33.

It was a win for youth and speed over strength and experience. Shields broke away from Torlopova in the second of four rounds by being faster on her feet.

That approach frustrated Torlopova in the ring.

By the third round, Shields had a five-point lead over Torlopova, and never looked back. Shields overwhelmed the Russian for a final score of 19-12.