Merrick Bremner matched the course record with an eight under par 64 when his home South African Open began at Serengeti on Thursday.
The 26-year-old leads by two from compatriot Matthew Carvell and former Ryder Cup Swede Henrik Stenson as he tries to make up for the disappointment of a year ago.
Bremner, 500th in the world, was one off the halfway lead then, but fell back to 20th with weekend rounds of 72 and 75.
Back at the same venue, he grabbed six birdies to turn in 30 and took advantage of the two par fives on the inward half to throw down the gauntlet.
"I played fantastically on the first nine - I could have shot 28," he told the Sunshine Tour website.
"I started thinking a bit more and playing clever golf as opposed to using too much aggression, which is what I normally do.
"It's got a lot to do with the work I've been putting in behind the scenes. I've been working with a sports psychologist and that's probably led to my change in thought patterns on the golf course.
"I can see the bigger picture now. It's not just about brawn - it's sometimes about the brain as well."
Not that brawn should be over-rated, as Stenson showed by driving the green at the 375-yard 17th and making a 14-foot putt for an eagle two.
Trying to discover the form which made him world number four following his victory at the Players Championship in Florida three years ago, the 36-year-old certainly cannot be faulted for lack of effort.
Since the start of October he has played tournaments in Scotland, Portugal, America, China, America again last week and now South Africa. Dubai beckons next week.
Scotland's Craig Lee, 116th on the European money list in the week that the top 119 will earn cards for next season, eased the pressure with a five under par 67 highlighted by an eagle two at the 382-yard second.
He will resume in a tie for fourth with Stenson's fellow countryman Michael Jonzon and South African Alex Haindl.
Major winners Charl Schwartzel and Martin Kaymer recorded 68 and 70 respectively, the German's score being equalled by England's Tommy Fleetwood, 124th on the Order of Merit.
Branden Grace, trying for an incredible sixth win of a season that began with him fresh out of the European qualifying school, managed only a level par 72, the same as Schwartzel's brother Atti.