Top boxers Sachin Siwach (57kg) and Shiva Thapa (63Kg) also comfortably sailed into the last four here.
Rohit from the Railways adopted a counter-attacking strategy against his taller opponent from Himachal. He succeeded in landing more punches to unsettle Ashish with a mix of close-range attack.
Rohit landed more clear punches in the third round to register an upset 4-1 win over Ashish.
"It is my first tournament in the new weight category and defeating a big player is a huge morale booster," said Rohit, who had won gold medal in the last edition.
"I worked a lot on my strength and did a lot of weight training in my preparation ahead of the National. I am glad that my counter-attacking strategy worked today. Hopefully, I will win the gold medal again."
In other bouts, Shiva showed his composure and experience as he breezed past the challenge of Delhi''s Yogesh Tokas 4-0 in a one- sided bout.
The World Championships bronze medallist will face Uttar Pradesh’s Abhishek Yadav in the semi-finals.
2016 World Youth Boxing Champion Sachin was fierce and aggressive and did not put a foot wrong in the 5-0 win over Michael Dominic of Telangana.
The services boxer will take on Punjab''s Sagar Chand for a place in the finals on Wednesday.
In the bantam weight category, 2018 Commonwealth game bronze medallist Mohammad Hussamuddin, representing Services, continued the winning spree, scripting a unanimous victory over Haryana''s Neeraj.
Railways'' Naman Tanwar (91kg) blasted his way past Rajasthan''s Akhil Poonia 5-0 to ensure a semi-final berth.
Tanwar will be up next against last year''s bronze medallist, Uttarakhand''s Kapil Pokhariya, who trounced Maharashtra''s Mrunal Zarekar 5-0 to reach the semis.
Services boxer PL Prasad (52 kg) was no match for his opponent Sudeep Kumar from Uttar Pradesh who was defeated by a 5:0 verdict.
Chandigarh''s Pankaj Chauhan (75kg) reached the semi-finals after getting a walkover in the quarter-final bout against Punjab''s Lakhbir Singh.
He will face Haryana''s Ankit Khatana as he aims to secure his place in the final. PTI ATK ATK
Disclaimer :- This story has not been edited by Outlook staff and is auto-generated from news agency feeds. Source: PTI