Christofer Blomstrand fired a stunning 62 to set the clubhouse target on day three of the Joburg Open but that was not enough to keep pace with Shubhankar Sharma at Randpark Golf Club.
The Swede began the day just one shot above the cut line and eight shots off the lead but with preferred lies in play on a softened Firethorn Course, low scoring was the order of the day.
Blomstrand turned in 29 and when he got to 11 under with four to play, it looked like he could be on course for a 59 on his 26th birthday.
He ultimately ran out of steam and a bogey on the last left him at 15 under, three shots behind Sharma who made five birdies in his first ten holes.
The Indian shot a stunning bogey-free 61 on Friday and picked up where he left off to establish a commanding lead at 18 under.
England's James Morrison was 14 under, a shot clear of Finn Tupio Pulkkanen and two ahead of local favourite Erik van Rooyen.
Sharma is playing just his tenth European Tour event but has now made nine cuts and enjoyed a top ten in Hong Kong two weeks ago.
As well as the trophy this week, the top three finishers will earn a place at next year's Open Championship at Carnoustie Golf Links.
Some players had to return to complete their second rounds on Saturday morning after a storm delay on day two and when the first 36 holes were in the books, 82 players had made the cut, with an additional cut now being imposed after 54 holes for the top 72 and ties.
Once round three was under way, it was Blomstrand on the move, making an eagle on the fourth to go with birdies on the second, third, fifth, seventh and ninth to turn in 29 and move to within two of the lead.
Blomstrand bogeyed the tenth but bounced straight back with a lengthy putt on the 11th before Sharma joined the lead.
A birdie looked a long shot when he was well short of the green and in the rough in two on the second but he got up and down brilliantly for birdie on the par five.
Overnight leader Pulkkanen missed the green with his second into the third to drop his first shot of the week and when Sharma holed from three feet after a stunning approach, the lead was two shots.
Blomstrand took advantage of the par five 12th to join Pulkkanen two off the lead but that was soon three back as Sharma made the most of the fourth after getting on in two.
Qualifying School graduate Blomstrand hit a brilliant approach into the 13th to tap-in range but Sharma was not in the mood to be caught and a tee-shot to three feet on the par three fifth extended the lead back to three shots.
Blomstrand was relentless and when he got on the 14th in two and holed a 20-footer for eagle, he was 11 under for the day and talk of a 59 began to circulate around the course - although the preferred lies would have denied him his place in the history books.
Pulkkanen chipped in on the seventh to steady the ship, with Sharma missing a good birdie opportunity and Blomstrand getting up and down from a bunker to par the 15th.
Morrison made a birdie-bogey start but picked up further shots on the fourth, seventh and eighth to turn in 33 before an eight-footer on the tenth moved him alongside Pulkkanen.
Further pars for Blomstrand on the 16th and 17th effectively ended any hope of him breaking 60, and Sharma hit an approach to four feet on the ninth for a fifth birdie of the day and a two-shot lead.
Blomstrand's closing bogey after going left off the tee then left Sharma in total command.
Morrison made it four birdies in five holes on the 11th, while Van Rooyen had two birdies and two bogeys in his first ten holes.
Marcus Armitage, Oliver Bekker and Christiaan Bezuidenhout were at 11 under.
