The 31-year-old Indian beat Si Haijuan of China 3-0 to win by a unanimous decision. (Also Read: Kushbir Kaur Wins Silver in 20km Walk)
The Chinese fighter gave Mary Kom a stiff fight but the Indian showed her class and made her punches count.
The judges gave 39-37 scores in all three rounds in favour of Mary Kom. (Read: Indian Women Archers Lose in Bronze Playoff)
A semi-final berth means Mary Kom has assured India of a minimum bronze and a possible silver or gold if she makes it to the final.