Randhawa, after an amazing run on the first two days, returned a card of one-under 71 that put him at 13-under overall and gave a six-stroke cushion over Kapur going into the final day.
Kapur, coming into the tournament after a month's lay-off to recover from a back injury, found his touch to fire a six-under 66 which catapulted him from tied-11th to lone second position at seven-under 209.
Gaurav Dhiman, the Bangalore pro who had occupied the spot behind Randhawa yesterday, had his title hopes ruined by a five-over 77.
And so did Richard Backwell, who was lurking behind the leader yesterday at six-under. The Australian was nine strokes behind Randhawa after shooting two-over.
The innovative format of pairing - an amateur with a pro in each group - meant the timing went for a six.
The leading group, which teed off at 10 past nine in the morning, returned the card at just about three in the afternoon. More importantly, the pros had a tough time retaining their focus.
Randhawa started strongly, birdying the second hole but missed a putt from nine feet at the par-4 seventh to be level for the front nine.
Things didn't seem to go right initially on the back nine as well when he bogeyed the 13th, under-chipping from inches outside the green to 15 feet from the pin.
He then had a chance for eagle on the 14th but over-chipped and then two-putted. Still he managed to birdie it to be even par.
Randhawa birdied the next but followed it up with some horrendous putting on the last three holes, missing birdies on all three.
After two-putting on the 16th, Randhawa three-putted on the 17th. He saved himself the blushes on the 18th.
"The conditions were tough, it was very windy," the ace golfer said. "Putting was tough, there was no margin for error. But any under-par score is good. I will take it.
"I want to try and keep playing my normal game. Go out and do my best, take what comes my way."
Kapur was four-under when he reached the club house after birdying the third, fourth, eighth and ninth holes.
He started and finished the back nine with birdies interspersed with a bogey and birdie on the 13th and 14th respectively.
"My hitting was good. It was quite windy but I had good control on my ball flight," the 2002 Asian Games gold medallist said.
"I holed a few putts that I missed yesterday," he added.