Sun City - Henrik Stenson covered the back nine at the Gary Player Country Club in five-under par to charge eight strokes clear in the third round of the Nedbank Golf Challenge on Saturday.
The Swede had seven birdies, including five on the back nine, to sign off a seven-under-par 65.
His 54-hole total of 17-under-par 199 put him well within striking distance of the tournament record of 25-under-par 263 set by Ernie Els in 1999.
Stenson, 32, will tee off in the final round alongside compatriot Robert Karlsson, whom he partnered to Sweden's second World Cup triumph last week.
European Tour Order of Merit winner Karlsson also did well on the back nine for a five-under 67 to finish at nine under.
Rory Sabbatini, playing in Stenson's shadow for 18 holes, stayed in touch but faltered at the final hole when his approach found the greenside trap. He failed to up-and-down and the resulting double bogey meant the South African signed for 72 and slipped to third at six under.
Lightning again stopped play, after a suspension on Friday that meant players had to complete the second round early on Saturday.
Play resumed after a 57-minute delay and Stenson raced to a four-stroke lead with a course-record 63 and kept ahead with a second-round 71.
Nedbank Challenge third round scores at the par-72 Gary Player Country Club:
199 - Henrik Stenson (SWE) 63-71-65
207 - Robert Karlsson (SWE) 72-68-67
210 - Rory Sabbatini (RSA) 68-70-72
211 - Kenny Perry (USA) 73-70-68
212 - KJ Choi (KOR) 72-67-73, Lee Westwood (GBR) 70-72-70
214 - Sergio Garcia (ESP) 72-70-72, Trevor Immelman (RSA) 72-73-69
217 - Luke Donald (GBR) 72-74-71
218 - Justin Rose (GBR) 73-73-72
219 - James Kingston (RSA) 72-77-70
224 - Miguel Angel Jimenez (ESP) 75-76-73