Six-time world champion M C Mary Kom (51kg) powered into the Olympic Games' pre-quarterfinals after staving off a stiff challenge from Dominican Republic's Miguelina Hernandez Garcia in the opening round here on Sunday.

The 38-year-old, who is a 2012 Olympic bronze-medallist, prevailed 4-1 against a rival who is 15 years her junior and a Pan American Games bronze-medallist.

In a bout that was exciting from start to finish, Mary Kom displayed some brilliant tactics to overcome the spirted fight that Garcia put up.

If she held back in the opening round to get a good measure of her rival, the veteran was aggression personified in the final three minutes after Garcia bagged the second round with some fierce punching of her own.

Mary Kom's trusted right hook aided her well through the bout and she also displayed a sharp mind by forcing Garcia to lunge at her, opening up the space for the Indian to land clear punches.

The youngster from Dominica had the stomach for a fight but was undone by her inability to strike clearly.

Mary Kom, a mother of four, will next be up against third-seeded Colombian medallist Ingrit Valencia, who was a bronze-medallist at the 2016 Rio Games.