Richard Sterne and Trevor Fisher Jr. both shot 4-under 68 on Saturday to remain tied atop the Joburg Open leaderboard through three rounds.
The South African duo are knotted at 19-under 196 -- five strokes clear of 2011 Masters champion Charl Schwartzel, George Coetzee, Felipe Aguilar and Jaco Van Zyl.
Schwartzel, a two-time winner of this event, is making his season debut. The South African carded a 68 on Saturday, while Coetzee, Aguilar and Van Zyl shot 70, 68 and 67 respectively.
Coetzee has recorded 21 top-10 finishes, including a tie for second in his last outing at the Qatar Masters, but he is still searching for his first European Tour win.
Peter Uihlein is alone in seventh place at minus-13 after tallying a third- round 68.
Rookie and first-round co-leader Maximilian Kieffer, a Challenge Tour graduate, fell into a tie for 35th at 8-under with his second straight level- par round.
A victory on their home soil would prove significant for Sterne and Fisher alike. The former is a five-time winner on the European Tour, but he hasn't triumphed since 2008, while the latter is a Sunshine Tour regular who has never won on the European circuit.
After splitting the East and West Courses at Royal Johannesburg and Kensington Golf Club over the first two days, the remaining field moved to the tougher, par-72 East Course for the weekend rounds.
This was the second straight week that Sterne held the halfway lead in a tournament. He jumped out to a 1-stroke advantage through 36 holes at the Dubai Desert Classic, but lost the lead to Stephen Gallacher during the third round and eventually finished in second place.
"It was pretty good going out there," said Sterne, who won this event in 2008. "It's quite draining for two weeks in a row, but I'd rather be here than in the middle of the pack. But the heart is pumping quite fast out there."
On Saturday, both of the overnight leaders started with a birdie, but it was Sterne who jumped ahead first with a birdie at the par-5 sixth after nearly chipping in for eagle.
Sterne followed with a birdie at No. 7, but Fisher matched him there, then pulled even with a birdie against his compatriot's par on the eighth.
Another birdie on No. 9 had Fisher on top by a stroke, but his lead was short- lived thanks to consecutive bogeys on Nos. 10 and 11.
Sterne briefly took advantage and birdied the 11th to go ahead by two, but the jostling continued, as Fisher bounced back with back-to-back birdies to again share the top spot.
Both players dropped a shot on the par-4 15th before closing with matching birdies on the last to reach 19-under.
"A bit of nerves set in there," said Fisher, who tied for third at this event last year. "You try not to think about the lead, but it's there in front of you.
"I was a bit jumpy with the swing and wasn't waiting at the top, so I hit a few bad shots there. But I came back nicely with a few birdies. It's just a feeling, and you've got to try and feel comfortable out there as much as possible."
NOTES: Fisher's second-round 62 was one stroke shy of Schwartzel's West Course record ... Schwartzel finished 2012 with back-to-back wins, which came by a combined 23 shots ... This tournament is co-sanctioned by the European Tour and Sunshine Tour of South Africa ... Defending champion Branden Grace missed the cut on Friday after turning in rounds of 72 and 70.