Delhi's Kapil Kumar, who fired a sedate even-par-72 on Saturday, continued on top of the leaderboard for the third day in succession as he shared the lead with Perera at eight-under-208 at the Rs 40 lakh event.
Lucknow's Sanjeev Kumar produced a 67 on day three to occupy third place at six-under-210.
Delhi's Shamim Khan struck the day's best score of 66 to move into tied sixth at three-under-213.
Mithun Perera (71-70-67), lying overnight tied fifth and five off the lead, made an encouraging start with birdies on the first and fifth, the latter being a chip-in. A couple of missed chip-putts on the seventh and eighth brought the 32-year-old six-time winner on the PGTI back to even-par for the day.
Perera, known for his accurate hitting, then turned on the heat on the back-nine with five birdies, three coming as a result of long conversions while two were tap-ins. Mithun, who last won a title in March 2018, came close to making his second chip-in of the day on the 18th where he had to settle for a par. He is currently the only player in the field to have shot three sub-par rounds.
Kapil Kumar's (68-68-72) chipping woes continued for the second straight day as his four birdies were neutralized by four bogeys which were all a result of missed chip-putts. Kapil was the sole leader by two shots till the 16th hole before he faltered with bogeys on the last two holes.
Kolkata's Sunit Chowrasia (70) is the highest-ranked local player in tied fourth at four-under-212. Faridabad-based Abhinav Lohan (67), whose round featured a run of four straight birdies on Saturday, is also in tied fourth.
Mumbai's Anil Bajrang Mane (76) dropped from overnight second to tied sixth at three-under-213.
Bengaluru's M Dharma (76) slipped from overnight third to tied eighth at two-under-214.
Delhi-based rookie Kshitij Naveed Kaul, the highest-ranked player in the field being fourth in the PGTI Rankings, was placed tied 18th at one-over-217.
( With inputs from IANS )