The experienced Indian icon gave a perfect start and the platform to India's medal campaign at home, outsmarting Yu Wu from China 5:0 in the Light Fly (48 kg) category which was later cashed in on by Lovlina Borgohain, who accounted for Aussie Kaye Frances Scott in Welter class (69 kg), with another unanimous decision of the day.

Later in the evening session, Sonia beat Colombia's Yeni Castenada in the 57 kg category while Simranjit Kaur beat Ireland's Amy Sara Broadhurst 3:1 in the 64 kg category.

But Manisha Moun (54 kg), Bhagyabati (81 kg) and Pinki Rani Jangra (51 kg) were not so lucky on the day.

The aggressive 20-year-old could not get past top-seeded Stoyka Zhelyazkova Petrova and ended up on the losing side, the split verdict (4:1) going in favour of the Bulgarian, while Bhagyabati lost to Colombian Jessica Sinisterra, in a split verdict (2:3).

Pinki lost to a superior North Korean Mi Choi Pang, the latter winning 5:0.

What separated Mary Kom and Manisha was the patience that the 35-year-old employed during her bout and the aggression that Manisha displayed against Petrova.

With the crowd rooting for Mary, the tactical boxer didn't try to dominate to begin with biding time to inch her way, tackling the Chinese, a first-timer at the Worlds, before upping the ante in the second and third rounds for the unanimous decision.

Her lethal rights, when combined with the lefts and the jabs opened up the avenues for her to send down the blows on target areas.

In the semi-finals, Mary will meet North Korean Mi Hyang Kim, who won 5:0 against South Korean Chorong Bak. The Indian has a good record against Kim, having beaten the North Korean in the final of the Asian Championships last November.

"The World Championships are always tough. The Chinese come up with good new faces. I won't say it was very easy or very tough. I planned my strategy and fought accordingly," Mary said.

On her next opponent, the Manipuri said: "She could be coming with some plans against me because I had beaten her last year. But I am prepared for it."

Manisha, on the other hand, was full of aggression in contrast to the Astana silver medal winner's patience. In the first Manisha lagged behind her rival though midway she tried to catch up, trading combination punches.

However, the calculative Bulgarian went about methodically, landing a few lefts and a couple of straight on Manisha's face.

In the third, the former European champion was far superior reaching out to her Indian opponent which, perhaps, got the judges' nod, despite Manisha's last-round efforts.

Lovlina was as explosive as one expects a young boxer to be. The 21-year-old Assamese, who came into form early this year in Ulaanbaatar (Mongolia) and Silesian (Poland) events, took her time before going all out against Kaye Frances from the first round.

The Aussie was straightaway on the backfoot even as the Indian piled on her agony. She continued the trend in the last two rounds and impressed the judges who almost gave a clear verdict (27-30, 28-29, 27-30, 27-30, 27-30).

Talking on her next opponent from Taipei Chen Nien-Chin, the Assamese pugilist said that she got to watch her videos to plan her strategy.

Bhagyabati did admit to her folly of relaxing in the first round which cost her berth in the medal round. Indeed, she was slow to start with while the Colombian was at her attacking best.

The Indian did manage to trade off blows in the second and, mostly, in the third to make amends. But it was too little and too late as the decision as the marginally better Jessica won (28-29, 28-29, 30-27, 29-28, 28-29). In fact, only one judge awarded full points to the Colombian.

Pinki was up against Jakarta Asian Games silver medallist North Korean Mi Choi Pang, whose reach and speed is too well known.

As expected, the 24-year-old Pang was aggressive and landed her punches on target areas. The Indian, pushed to the ropes, came back partially in the second showing her intent.

In fact, she managed a few blows which could have brought the judges into focus. Her open guard and the distance she maintained were of no avail as the speedy Pang made the Indian nervy on more occasions than one.

In the semis, she will take on Virgina Fuchs, the only American boxer so far to enter the medal round.

In the 57 kg category, Sonia made amends for the senior pugilist's loss, as she defeated Colombia's Yeni Castenada in a split verdict. The Indian continued her fine run as she won the bout with a 4:1 decision.

Among the foreign participants, Thailand's Sudaporn Seesondee reached the medal round beating Finland's Mira Potkonen, the top seed here.

The only Olympics medallist from Finland, Potkonen was expected to go up to the final but it was disappointing to see her bowing out of the championships as the Thai won the quarterfinals in a split vereict (4:1).