Along with Magimairajan, others to make the knockouts from Group D are Floriza Andal of Philippines, Ka Kai Wan of Hong Kong and Carmelita Yumito of Brazil.
Also to qualify in the round-of-24 was Thailand's Waratthanun Sukritthanes after she delivered a shocking 3-0 blow to defending champion Wendy Jans of Belgium in a Group A contest.
Zha lost a tight first frame on the blue before bouncing back to take the second on the black and then fought his way back to win the next three for his third win in four outings.
The 17-year-old Zhao has not been in his usual touch - though he pulled off a win, he has to keep a watch on Group D result which is heading to the wire with England's John Whitty, India's Faisal Khan and Polish teenager Mateusz Baranowski, having won three matches apiece.
Joining the home pair in the round-of-64 were Iranian Sarkhosh, Kritsanut Lertsattayathorn of Thailand and Hong Kong's Lee Chun Wai, all notching their fifth win in their respective Groups.
Advani took out Thadeu Giannattasio Nobres of Brazil 4-0 after surviving early struggles as he took the first frame on the blue and second on black before crafting a 75 clearance in the third and 59 in the fourth while Chawla cruised to a 4-1 win over Australia's Matthew Bolton.