Maharashtra boy Banthia drubbed his Gujarat opponent Kevin Mrugesh Patel 6-2 6-1 to enter the last eight.
Second seed Megh Patel of Gujarat was level with 14th seed Ashutosh Tiwari of Uttar Pradesh at one-set all when he conceded the pre-quarter final tie.
Another seeded casualty was no.10 Rishabh Sharda who was beaten 7-6(3) 6-2 by Sanket Tomar of Chandigarh.
Gujarat's 14-year-old Dev Javia, set to represent the country at the "Road to Wimbledon" this year in the boys' section, ended the winning run of Arjun Honnappa of Karnataka, winning 6-7(5) 7-5 7-5 in a match lasting over 3 hours.
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In girls' singles, top seed Sama Sathwika of Telangana got past Kritika Chhabra of Maharashtra 6-4 6-2 to make the last eight stage.
Ninth seed Prinkle Singh of J and K upset sixth seed Akanksha A Bhan of Gujarat 6-1 6-4 while no. 11 Dedeepya Sai of Telangana ousted no.5 Humera Shaikh of Andhra Pradesh 6-3 6-4.
Local player Salsa Aher, seeded 16th, was the lone girl from the host state to make it to the last eight, when she stopped the run of giant-killer Syeda Shajiha Beg of Andhra Pradesh 6-3 6-3.