Shubhankar's stellar show vaulted him 55 places to the second place at seven-under 137 two-day total at the Gary Player layout of the DLF Golf and Country Club. Grillo, meanwhile, leads by a comfortable four shots on 11-under 133 total.
The 21-year-old Indian, lying tied 55th after round one, broke the previous course record of 65 held jointly by Grillo, who achieved the number in round one on Thursday, as well as Malaysian Gavin Green, who fired the score at the last edition of the Indian Open.
The top-ranked Indian golfer, who was five-over through his first nine holes in round one, staged a remarkable fightback to rise into contention by going 12-under over the next 27 holes.
Shubhankar, the highest-ranked player in the field at world No.66, was two-under for the day when he made the turn on Friday but then put his foot on the pedal on the back-nine with six birdies which included a tap-in on the 10th and a 30-feet conversion on the 12th.
Shubhankar, who had a tied ninth finish at last week's WGC event in Mexico City, said, "Today's round will definitely rank up there as one of my most significant achievements, especially when it is played at this course. This is a tough course and it is not easy to go low here. I'm very happy with the way I played. I shot a few low numbers in my career and this one is right in my top five.
"I know I had to get a good start. I normally try to do as best as I can on the front nine. I did my best, but it was still two-under-par. But I was hitting it well, even though the back nine is tougher than the front nine, I knew I could still make birdies."
The 25-year-old Grillo, who started on the 10th hole, got off to a great start with consecutive birdies on holes 11 and 12. Grillo scored three more birdies and one bogey before ending his round.
Spain's Pablo Larrazabal (71) and England's Andrew Johnston (66) are a shot behind Shubhankar in tied third, while four golfers, including South Africa's Keith Horne (73) and Thailand's Panuphol Pittayarat (70) are currently in tied fifth on 139.
Khalin Joshi's error-free 68 ensured he was the second Indian in the top-10 on day two. Joshi was in tied ninth at four-under 140.
Nine out of the total 144 golfers could not finish their second round on Friday due to the fading light. The cut is likely to be applied at three-over 147.
Khalin Joshi (72-68), who had missed the cut at the Indian Open by one shot for the last three years in succession, too made significant ground with his 68 on Friday. The score took him from tied 35th in round one to tied ninth on day two.
Ajeetesh Sandhu, the best Indian on day one, carded a 76 in round two to slip to tied 31st at even-par-144. Anirban Lahiri (73), the 2015 champion, was a further shot back in tied 35th.
Teenaged amateur Kshitij Naveed Kaul (two-over-146) as well as Karandeep Kochhar, another teenager, and Udayan Mane (both with totals of three-over-147) will also make the cut among the Indians.
Three-time Indian Open champion Jyoti Randhawa, who was at an even-par total through 15 holes when play was suspended, is likely to be the eighth Indian to make the cut.
Arjun Atwal and Shiv Kapur, both with totals of four-over 148, are likely to miss the cut.
The other prominent Indian names who will miss the cut, are defending champion SSP Chawrasia (seven-over 151), Gaganjeet Bhullar (nine-over 153) and Jeev Milkha Singh (20-over 164).
(This story has not been edited by Social News XYZ staff and is auto-generated from a syndicated feed.)
