Udayan drew curtains on Solanki's campaign with a 6-1 6-3 win even as top seed B R Nikshep survived a scare against Venkata Gnan Paramatmuni before winning the contest 6-4 7-6(2).
The others to make the cut for the semi-finals included fourth seeded Aryan Goveas, who defeated Sanil Jagtiani 6-3 6-2 while third seed Paramveer Singh Bajwa overwhelmed Parikshit Somani 6-1 6-0.
In the under-14 boys singles, it was end of the road for top seed Sumit Pal Singh. Sumit fell on the wayside with Danish Ahmad scoring a 4-6 6-2 6-2 win to reach the last-four stage.
Third seed Nitin Kumar Sinha and fourth seed Yugal Bansal also made it to the next round. While Nitin had it easy against Shramay Dhawan (6-0 6-2), Yugal also eased past Sivadeep Kosaraju 6-1 6-3.
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In the girls under-16 quarter-finals, second seed Zeel Desai was shocked 2-6 7-6(3) 6-2 by Ramya Natrajan.
Ramya later recorded a convincing 6-1 6-4 win over Rishika Ravi in the under-14 event to qualify for the semi-finals in both the categories.
Also making it to the semi-finals in the under-14 girls event was third seed Mihika Yadav, who beat Manasvi R Siddareddy 6-1 6-1.
In the girls under-16 event, top seed Akshara Iska and third seed Vanshika Sawhney moved into the semi-finals.