The 19-year-old's three-round total read at an impressive 8-under 208 at the testing 7227-yard course.
Trushul's city-mate Udayan Mane caught fire on his back nine making two birdies and an eagle in the first three holes to return a card of 2-under 70 for an overall total of 212. Ainesh Ahluwalia was lying third at level par 216.
Ankur Chadha, Vikram Rana and Aman Raj were tied for the fourth spot at 217. Another local lad Jaibir Singh matched the day's best of 67 to move up to the seventh spot at 218 along with Hemendra Choudhary.
Trishul admittedly was wayward in the initial stage of his round but was lucky to save the pars. Then began a birdie blitz - four of them in five holes including a hat trick beginning from the third, thanks to his hot putter.
Meanwhile, Udayan dropped a shot and when the duo took the turn, Trishul was leading by six which was reduced to three by the 12th. It was not because Trishul's mistakes as he did good to make a birdie on the 11th but because of Udayan's heroics which read birdie-eagle-birdie.
Undeterred by the late charge from his playing partner, Trishul had an eventful four holes from 14th to 17th where he made two bogeys and as many birdies compared to Udayan's a birdie and a bogey.
"I am glad to have played a good round and happy to lead by four shots," said Trishul. "I was not bothered about Udayan as I was engrossed with my own game. I could have saved two shots as I think the bogeys on the 14th and 17th could have been avoided," he added.
"I am going to play my game and not think of anything else," said Trishul who is looking for a maiden win on the IGU Tour.
Top scores (after 54 holes)
208 Trishul Chinnappa (69, 72, 67); 212 Udayan Mane (71, 71, 70); 216 Ainesh Ahluwalia (72, 75, 69); 217 Ankur Chadha (72, 76, 69), Vikram Rana (72, 75, 70), Aman Raj (71, 72, 74); 218 Jaibir Singh (74, 77, 67), Hemendra Chaudhary (73, 75, 70); 219 Manu Gandas (74, 72, 73); 220 Nikhil S Sekhawat (71, 78, 71); 221 Syed Saqib Ahmed (75, 72, 74), Pratap Atwal (75, 71, 75); 222 Pukhraj Singh Gill (73, 76, 73); 223 Advait Luthra (72, 78, 73); 224 R Marimuthu (78, 73, 73), Samarth Dwivedi (72, 78, 74)
--IBNS (Posted on 05-09-2013)