World number three Lee Westwood of England birdied the last hole to share the lead on 68 with South African Charl Schwartzel after the first round of the Nedbank Challenge on Thursday.
Defending champion Westwood made the green at the dog-leg par four in two and sank an 18-foot putt for a four-under-par round at the 7162-metre Gary Player Country Club course.
US Masters title holder Schwartzel reached the turn one over in overcast and sometimes wet conditions after a double-bogey seven at the ninth, but recovered with five birdies on the inward nine.
Swede Robert Karlsson was among the first two golfers in a 12-man invitation field to tee off in unseasonal cool conditions and carded a 69 to occupy third place.
World number one Luke Donald, fellow Englishman Simon Dyson, Graeme McDowell from Northern Ireland, American Jason Dufner, German world number four Martin Kaymer and Kim Kyung-Tae from South Korea all shot 70.
Dane Anders Hansen and Italian Francesco Molinari carded a level-par 72 apiece and reigning British Open champion Darren Clarke from Northern Ireland returned a 74 on the opening day of the event known as the 'African Major'.
South African bookmakers installed Schwartzel as 9-2 favourite for the $1.25-million first prize and he played steadily until the nightmare ninth.
A couple of visits to the rough and one to a water hazard meant he needed five strokes to reach the green at the par-five hole and two putts left him one over at the turn.
Schwartzel bounced back with a birdie at 10, repeated the feat at three consecutive holes from 12 and sank a 20-foot putt at 16 for his fifth on the way home.
"The way I played on the back nine reflected my recent form. I have been hitting the ball really well and once my putts start rolling, I get into good positions at tournaments," said Schwartzel.
Westwood recovered from an opening-hole bogey to eagle the ninth and turn two-under and made three birdies and one bogey on the second nine as he chases a second consecutive Challenge title.
Karlsson had three birdies in a row from the second but two back-nine bogeys spoilt his card while Donald did well apart from a double-bogey six at the penultimate hole after driving his tee shot into water.