JOHANNESBURG, 28 Feb 2015 (AFP) - Of the top 14 names on the leaderboard after the third round at overcast Royal Johannesburg and Kensington Club, eight are South African and the other six English.
South Africans have dominated the event, winning the last five editions and six of eight overall. No Englishman has won the Joburg Open.
Coetsee carded a two-under 70 over the 6345 metres - 6940 yards east course for a 201 total in the co-sanctioned European Tour-Sunshine Tour championship.
Fellow South Africans Jacques Blaauw (67) and Tjaart van der Walt (71) and Englishmen David Howell (68) and Steve Webster (65) are on 203 and share second place.
Among nine golfers on 204 is defending champion George Coetzee, who fired a second consecutive 69 to finish three strokes adrift of the leader.
Coetsee, a native of Eastern Cape surfing paradise Jeffreys Bay, showed erratic third-round form, especially on the inward nine.
After a one birdie-one bogey outward half, he made another bogey, birdied three holes, bogeyed one and finished with a birdie.
The South African is chasing his first European Tour victory after ending a 17-year Sunshine Tour title drought by winning last season in Zambia.
"I need to keep a positive mind," stressed Coetsee. "My caddie and I are enjoying it out there and hopefully we still will be come tomorrow afternoon.
"There is a lot at stake, more than you can think of, but it is just a game at the end of the day.
"Last night I only slept for about four hours but tonight I think I'm going to have a lot of sleep."
Coetsee is chasing a 206,050-euro ($230,000) first prize and automatic entry to the British Open at St Andrews this July.
A seven-under 65 from Webster early in the day was the lowest third-round score and it gave him the clubhouse lead untll late in the day.
Without a top-10 finish for more than a year, Webster was a model of consistency as he picked up five outward-nine birdies, two more coming back, and did not drop a shot.
And his score could have been even lower.
"I missed three or four 12-foot putts, which was frustrating," he admitted.
Leading Joburg Open third-round scores Saturday at the par-72, 6345 metres- 6940 yards Royal Johannesburg and Kensington Golf Club east course (RSA unless noted):
201 - Wallie Coetsee 66-65-70
203 - Jacques Blaauw 67-69-67, David Howell (ENG) 66-69-68, Tjaart van der Walt 63-69-71, Steve Webster (ENG) 72-66-65
204 - Thomas Aiken 67-67-70, George Coetzee 66-69-69, Simon Dyson (ENG) 65-67-72, Anthony Michael 68-67-69, Garth Mulroy 64-68-72, Andy Sullivan (ENG) 71-65-68, Chris Swanepeol 70-67-67, Anthony Wall (ENG) 67-66-71, Paul Waring (ENG) 68-69-67
205 - Maximilian Kieffer (GER) 70-67-68
206 - Kristoffer Broberg (SWE) 67-67-72, Darren Fichardt 68-71 67, Kevin Phelan (IRL) 67-68-71, Justin Walter 71-66-69, Jaco van Zyl 69-67-70