She took that confidence into the semis and avenged her Thailand Open semi-final defeat to former World Championships bronze medallist Chuthamat Raksat of Thailand.
Lovlina Borgohain lost the 69kg category bout in a split decision of 2-3, which ended her run in the tournament.
In the 54kg category, Boro in her maiden World Championships faced a 0-5 defeat at the hands of experience Hsiao-Wen.
Mary Kom on Saturday questioned her semi-final loss in the ongoing Women's World Boxing Championships.
The judges' points at the end of the semi-final bout stood at 29-28, 30-27, 29-28, 28-29, 29-28 in Rani's favour.
Turkey's European champion Busenaz Cakiroglu defeated Mary Kom 4-1 in the 51-kg category.
MC Mary Kom hardly broke a sweat as she swept aside her opponent from Thailand to make a strong start in the ongoing AIBA World Women’s Boxing Championships in Ulan-Ude, Russia.
Mary dominated much of the bout with her punches being more accurate than her opponent on a consistent basis. The judges' points at the end stood 29-28, 29-28, 29-28, 30-27, 30-27 in her favour.
On Saturday, Panghal had to settle for a silver medal in the championships as he lost the final match to Uzbekistan's Shakhobidin Zoirov.
Amit Panghal had to settle for a silver medal in the World Boxing Championships as he lost the final match to Uzbekistan's Shakhobidin Zoirov.
At the ringside in Ekaterinburg (Russia), where the event is being held, India high-performance director Santiago Nieva was a pleased man.
A controversy broke out over Mary's selection for the women's World Boxing Championships in Russia after her competitor in the 51kg category, Nikhat Zareen, was refused a trial bout.
Boxers were selected after three-day trials which concluded on Thursday at the Indira Gandhi Indoor Stadium.
Manju Rani (48kg), Jamuna Boro (54kg), Neeraj (57kg), Manju Bomboriya (64kg), and Nandini (81kg) will be competing in the mega-event for the first time.
Mary Kom, who claimed her sixth world title last year in Delhi, will be looking to qualify for the 2020 Tokyo Olympics in the World Championships in Yekaterinburg, Russia.