Six-time champion Mary Kom assured herself a record-extending eighth medal at the championships after progressing to the semifinals. She defeated Ingrit Valencia Victor of Colombia with a unanimous 5:0 verdict in her last-eight match.
Mary Kom, chasing her first world medal in the 51 kg division, used her experience to great advantage and defended brilliantly against the Rio Olympic bronze medallist. The judges' points at the end stood 29-28, 30-27, 29-28, 30-27, 29-28 in Mary Kom's favour.
She will now face second seed Busenaz Cakiroglu of Turkey on Saturday in the semifinals.
After her, Manju assured India of their second medal at the event after stunning top seed Kim Hyang Mi of North Korea to make it to the semi-finals in 48 kg division.
Sixth-seeded Manju, playing her first World Championships, defeated Kim by a 4-1 verdict in their last-eight match. Kim had won bronze in the 2018 edition of the world championships that was held in New Delhi.
The judges' points at the end of the quarter-final bout stood 29-28, 30-27, 29-28, 28-29, 29-28 in Manju's favour.
The third medal assurance came for India as Jamuna (54 kg) got the better of Germany's Ursula Gottlob by 4-1. The judges points for the Assam pugilist read 30-27, 29-28, 28-29, 29-28 and 29-28.
Lovlina (69 kg) also maintained India's good run at the championship as she defeated European Games Champion Karolina Koszewska of Poland by 4-1 to enter the semifinal. The judge's points for her was 28-29, 29-28,29-28, 29-28 and 30-27.
However, there was disappointment for Kavita Chahal who lost her quarterfinal bout to Belarus' Kavaleva Katsiaryna 1:4 in the +81 kg weight category.
Earlier in the day after entering the semis, Mary Kom had said: "I am quite happy after winning the quarterfinal. I will try my best to do better and get a gold medal."
( With inputs from IANS )