23-year old Shruthi, starting third on the grid, made it to the front on the last lap after easing past leader Alisha Abdullah (Team Abdullah) for a thrilling win.
Alisha came in second ahead of Ryhana Bee (Sparks Racing). Pole-sitter and championship leader Ann Jennifer retired after a crash in the second lap, but retained her top position on the leaderboard with 50 points, albeit just two ahead of Shruthi.
"I am very happy to score my first-ever win in the National Championship after a few podium finishes in the past. I started third and gradually moved to the front after overtaking Alisha," said a delighted Shruthi.
Meanwhile, Defending champion Jagan Kumar finally got his campaign on track as he notched his first win of the season in five starts while leading a 1-2 finish for TVS Racing along with KY Ahamed in the premier Super Sport Indian 165cc class of the MRF MMSC FMSCI Indian National Motorcycle Racing Championship.
The results (Provisional, all 6 laps unless mentioned):
Pro-Stock (301-400cc), Race-1: Prabhu Arunagiri (Team Alisha Abdullah) (11mins, 37.278secs); 2. Amarnath Menon (Gusto Racing India) (11:37.392); 3. Satyanarayana Raju (Gusto Racing India) (11:39.378).
Super Sport Indian (165cc), Race-1: 1. Jagan Kumar (TVS Racing) (11:46.715); 2.KY Ahamed (TVS Racing) (11:46.807); S Mathana Kumar (Honda Ten 10 Racing) (11:50.406).
Pro-Stock (165cc), Race-1: 1.Mithun Kumar (Idemitsu Honda Ten 10 Racing) (12:09.580); 2. Naresh Babu (RACR) (12:10.041); 3.Sivanesan S (TVS Racing) (12:19.089).
Girls (Stock 165cc) (5 laps): 1. Shruthi Nagarajan (Apex Racing Academy) (11:28.978); 2. Alisha Abdullah (Team Alisha Abdullah) (11:29.648); 3. Ryhana Bee (Sparks Racing) (11:29.901).
MMSC One-Make Championship (Novice), TVS (Apache RTR 200) Race-1: 1. Karthik Mateti (Hyderabad) (13:44.310); 2. Anand R (Chennai) (13:49.157); 3. Suhail Ahmed (Chennai) (13:49.298). Girls (5 laps): 1. Ann Jennifer (Chennai) (11:52.938); 2. Ryhana Bee (Chennai) (11:53.005); 3. Lani Zena Fernandez (Puducherry) (12:43.126).
Idemitsu Honda India Talent Cup (CBR 150) , Race-1: 1.Mohamed Mikail (Chennai) (12:54.158); 2. Kartik Vasant Habib (Gadag) (13:04.798); 3.Anandhu KK (Chennai) (13.23.689). Race-2: 1. Mohamed Mikail (Chennai) (13:03.204); 2. Anandhu KK (Chennai) (13:21.196); 3. Kartik Vasant Habib (Gadag) (13:28.357).