Merrick Bremner birdied six of his first nine holes for a course record-equaling 64 in the opening round of the South African Open.
The home player raced to 8 under par and a two-shot lead over Sweden's Henrik Stenson and another South African, Matthew Carvell, at Serengeti Golf and Wildlife Estate on the outskirts of Johannesburg.
Former Masters champion Charl Schwartzel recovered from a double-bogey five on his third, the 12th, to card a 4-under 68 for a share of seventh.
Former top-ranked player Martin Kaymer was 2 under after his 70. Branden Grace was level par.
Bremner consolidated his outstanding start with two more birdies coming home and had no bogeys to raise early hopes of a maiden European Tour title at his home Open.