Mary Kom of India started her campaign for a seventh International Boxing Association (AIBA) Women's World Championships title with a unanimous victory against Jutamas Jitpong of Thailand here.
Thirty-six-year-old Kom first earned a world title in 2002, with more following in 2005, 2006, 2008, 2010 and 2018.
She is also a five-time Asian champion and claimed a Commonwealth Games gold medal for the first time in Gold Coast last year.
The boxing legend has moved up to the flyweight division here and is seeded third.
Kom's next opponent will be Ingrit Valencia of Colombia, who unanimously defeated Gabriela Dimitrova of Bulgaria.
Recently crowned European Games champion and second seed, Buse Naz Çakıroğlu of Turkey, was also successful, easing past Anush Grigoryan of Armenia 5-0.
Cai Zongju of China beat Tursunoy Rakhimova of Uzbekistan 4-1 to set up a quarter-final clash with Çakıroğlu.
In the middleweight division, Commonwealth and European champion Lauren Price overcame Saweety Boora of India 4-1.
The Welsh third seed will face Iveta Lešinskytė next, with the Lithuanian progressing after the referee stopped her contest due to an injury to her opponent, Elzbieta Wojcik of Poland.
Sennur Demir of Turkey then defeated Australia's Caitlin Parker 4-1, before Khadija El-Mardi of Morocco recorded a unanimous victory against Victoriya Kebikava of Belarus.
Demir and El-Mardi will fight each other in the quarter-final.
Nesthy Petecio of the Philippines progressed in the featherweights, following a narrow 3-2 win against China's Qiao Jieru and is scheduled to meet Sena Irie, with the Japanese boxer beating Leonela Sánchez of Argentina 4-1.
A unanimous result went to England's Karriss Artingstall against Mijgona Samadova of Tajikistan.
Yodgoroy Mirzaeva will be Artingstall's next bout after the Uzbek got past Caroline Veyre of Canada 4-1.
The quarter-final stage in all three divisions is on Thursday (October 10).