Nikhil Rama carded a bogey-free 8-under 62 featuring an eagle at the par-4 third hole to take a one-shot lead at 13-under at the Joburg Open.
The home favourite is playing in his tenth DP World Tour start and has made the cut just twice so far. His best finish was T33 at last year's event.
He is playing this week thanks to a career-best fourth place finish at the Sunshine Tour's recent Vodacom Origins of Golf Finals.
"What can I say, it was a great round," said Rama. "It's my lowest score on Tour so far so I'm really excited about that. I'm enjoying the pressure, enjoying the fans which is great and just trying to have fun.
"After a short missed putt on one and two, the eagle that went down on number three from 202 metres just got the positive vibes going.
"I'm giving myself plenty of chances, I think I only missed one green today and one green yesterday so I'm giving myself some chances.
Overnight leader Thriston Lawrence closed with a 66 to move down one place at 12-under.
Dean Burmester scored a 62 in spite of a bogey at the par-4 8th and lies in a share of third place at 10-under alongside Jacques Kruyswijk (64).
Zander Lombard closed with a bogey-free 65 to complete the all-South African top-5 at 9-under.