South African Charl Schwartzel's brilliant ten under par 61 gave him a share of a three-way lead after two days of the Joburg Open.
On a day when almost three hours were lost due to a thunderstorm, defending champion Schwartzel tore up the West Course with ten birdies, including a tee shot to eight feet at the par three 16th.
That left him 13 under par at the halfway stage, along with compatriot Garth Mulroy and England's Jamie Elson, although not all of the field were able to complete their second rounds after the lengthy delay.
Mulroy and Elson both carded rounds of 64 on the tougher East Course layout - where the leaders will return for the weekend action once the second round is completed on Saturday morning and the cut made.
Schwartzel spoke on the eve of the tournament about some swing problems, but revealed he had received good advice from Hendrik Buhrmann - a winner on the Sunshine Tour and Asian Tour.
"I phoned Hendrik Buhrmann up on Wednesday afternoon after nine holes," he said.
"He had footage of my swing that he took when I was swinging really well, and he could clearly see that there were quite a few things out of place, and he really helped me.
"It was a fantastic round today. "It really fell into place and I hit some great tee shots and iron shots, and I used just about every opportunity I had on the greens."
The 29 year old Elson narrowly lost his European Tour card at the end of 2010 but had every reason to be delighted with his efforts at the Royal Johannesburg & Kensington Golf Club.
Having opened with a 65, Elson burst into life with five straight birdies from the fifth in his second round.
He picked up another shot at the 11th before play was suspended, and on the resumption splashed out of a greenside bunker to two feet for birdie on the par five last, completing a second consecutive bogey-free round.
Mulroy's round included an eagle at the eighth, seven birdies and two bogeys.
"I hit a good tee-ball," he said of his three at the par five eighth. "It was actually quite a long way from the hole and I made a long putt."
Three more South Africans share fourth place on 12 under in the co-sanctioned European Tour and Sunshine Tour event - James Kingston, Thomas Aiken and overnight joint-leader Tyrone Mordt.
Martin Maritz, the other player to hold a share of the first round lead, and Branden Grace are a shot further back, while Allan Versfeld completes the top ten alongside Scotland's David Drysdale.