The Bangalore lad's total moved to 14-under-202, while Delhi's Chirag Kumar also signed in a 65 to be three strokes off the lead in second position from an overnight tied seventh.
Local lad Rahil Gangjee sank an eagle from 45-feet and also made two birdies in his round of 68 that moved his score to 10-under-206 and helped him end the day in third place.
Overnight leader Sanjay Kumar of Lucknow slipped to joint fourth place after posting a 71.
Defending champion SSP Chowrasia lies tied 24th at one-over-217.
Overcoming a stomach bug, Lahiri shot an incredible round of 65 that placed him three shots clear of the field.
Eyeing his maiden title here, the 26-year-old, who was overnight second, claimed his first birdie after converting a 30-footer on the second.
Lahiri then made as many as three chip-ins, two of them resulted in eagles on the fourth and 15th and the third resulted in a birdie on the 14th.
"I was quite surprised with what I achieved on the course as I haven't been feeling too well since last night and was therefore just trying to get through the round. I didn't even have anything to eat today," he said of his upset stomach.
"I'm quite confident going into the final round now. Three chip-ins in a round are a rarity and so are two eagles. I'm thrilled with my effort today. I capitalised well on both the par-5s.
Chiragh too made the day memorable producing a spectacular bogey-free 65, the joint best score of the tournament.
The 2011 PGTI Order of Merit champion, Chiragh, earned five birdies on the front-nine that featured putts from 12 to 15 feet on the fifth and sixth.
He also landed it within four feet on the second and eighth. Chiragh chipped-in for birdie on the 13th and picked up another birdie on the 15th to end the day with a total score of 11-under-205.
"I've been playing well as I had a good outing at Jamshedpur last week where I finished in the top-5. I'll just look to play to my potential in the final round as Anirban has the ability to shoot very low scores and is going to be a tough contender.
