The Australian compiled a three-day total of eight-under-par 208 to take a one-shot lead over Singapore's Lam Chih Bing who seemed to be heading towards the final round with a huge advantage until he dropped four shots in his last five holes to sign for a 73 at the Delhi Golf Club.
India's Shiv Kapur and Thailand's Boonchu Ruangkit are tied for third place after they signed for a 72 and 73 respectively while another local hopeful Jyoti Randhawa is in fifth place after he carded a 67 at the full-field Asian Tour event.
Ormsby, who has been holding the lead since the first round, started well with an opening birdie but dropped three shots on holes three, four, seven and nine for an outward 39.
The 33-year-old Australian slipped to second place at the turn and trailed Lam by three shots at that stage.
He parred his next seven holes before he found relief on the closing 18th hole where he made his second birdie of the day.
"It was definitely a sign of relief when I birdied that hole. My putter was frustrating me a bit and it was overall a tough day. I started fantastic but my putter was a bit dry and I hope to get it going again tomorrow," said the 33-year-old Australian.
"The pressure's always mounting, that's golf. It's just how you deal with it. I just wasn't making the putts. But you just got to keep going on this golf course and see where you finish," added Ormsby.
Meanwhile Lam, who is hoping to end his five-year title drought this week, was in total control right till the 11th hole where he had enjoyed a four-shot advantage.
He opened with a birdie-bogey-par and charged straight to the top with birdies on holes five, eight and 11.
Lam's game however fell apart when he bogeyed four of his last five holes to slip one back of Ormsby heading into the final round at the Panasonic Open India.
"I'm not going to dwell on what has happened in the last few holes. More importantly, I'm still in it and I look forward to tomorrow," said Lam.
"I definitely had some positives that I could take out of and I need to work on my finishing as it hasn't been that great. I like the position where I'm in. Even though I missed a few putts coming in, the strokes were solid. It's probably more a misread than anything else," added the Singaporean.
Boonchu remained on course to become the oldest winner on the Asian Tour.
Korea's Choi Sang-ho holds that record when he won the 2005 Maekyung Open at 50 years and 145 days.
The record would however be broken if Boonchu wins his sixth Asian Tour title on Sunday.
The 56-year-old Thai veteran has already proved that he still had what it takes to stay in the upper echelons of the game by finishing 61st on the Order of Merit last season to earn full playing rights in 2013.
He finished tied-eighth at the Delhi Golf Club last month and looked set to better that result this week.
"I need to go back and allow my body to recover before I go back and play my last 18 holes. It'll be nice if an old man like me gets a win tomorrow," said Boonchu.
"Course conditions have been tough the last three days and whoever wins tomorrow is a definitely a deserving winner," added the Thai.
Kapur echoed Boonchu's sentiments as he spearheaded the local charge, keeping alive the nation's hopes of retaining the Panasonic Open India title on home soil since the event was inaugurated in 2011.
"It's like the US Open conditions out there. I have never seen conditions like this at the Delhi Golf Club. Not even during practice days. Par seems a good score in these conditions," said Kapur.
"My local knowledge will give me a one-shot advantage over the others on the final day. No target for the final round as in such windy conditions one has to play every hole on merit," added the Indian.
The top-three players at the Panasonic Open India will be extended invitations to the Asia-Pacific Panasonic Open, sanctioned by the Asian Tour and Japan Golf Tour Organisation, in Osaka, Japan in September.