George Coetzee maintained his one-shot lead as the third round of the Tshwane Open got under way but Sam Horsfield was making a charge through the field at Pretoria Country Club.
The local favourite opened 67-64 on his home course and was level par for his first three holes to stay at 11 under, one shot clear of Finn Mikko Korhonen and England's Horsfield.
Korhonen started with three pars while Horsfield turned in 30 to surge up the leaderboard and sit two shots ahead of clubhouse leaders Adilson da Silva and Sébastien Gros.
Chile's Felipe Aguilar and South African Daniel van Tonder were also eight under.
Horsfield came through all three stages of Qualifying School to win the Final Stage by eight shots and reached the semi-finals of the ISPS Handa World Super 6 Perth as he makes his start to life on the European Tour.
He made five birdies in his first eight holes on Friday and was off to a flier again, making five opening threes to hand him four gains as he moved up to nine under.
The front right was a popular spot on the first green and Aguilar found it but he three-putted on the slow surface, dropping another shot on the second to make it three in a row after Friday's closing blemish.
Coetzee had no such trouble, leaving himself 12 feet for birdie on the first but he had to settle with a par as Korhonen made a smart save after a poor tee-shot.
The 2015 champion played the second in the same textbook fashion as he had the first but this time he made the birdie putt and opened up a two-shot lead, with Korhonen again having to work for his par.
It was advantage Coetzee on the third as Korhonen found the rough but while his recovery was excellent, Coetzee's second was poor, and a three-putt led to a bogey and cut the gap to one.
Horsfield then joined Korhonen in second with a birdie on the ninth.
Gros joined Horsfield in starting with four birdies and he added another on the sixth before parring his way home to sign for a 66.
Playing partner Da Silva carded the same score in bogey-free fashion, making birdies on the second, fifth, sixth, 11th and 17th.
Van Tonder was five under for his round with one hole to play.
South Africans Thomas Aiken, Christiaan Bezuidenhout, Louis de Jager, Shaun Norris and Erik van Rooyen, England's Matthew Baldwin and Frenchman Victor Perez were seven under.
