Louis Oosthuizen, playing his home Open for the first time in eight years, fired a nine-under 62. Els shot a 66.
JOHANNESBURG — Louis Oosthuizen, the 2010 British Open champion, led the South African Open by a shot after a 9-under 62 in the first round on Thursday.
Oosthuizen, playing his home Open for the first time in eight years, made a brilliant start at Randburg Golf Club in Johannesburg with nine birdies, including six in an eight-hole surge on the back nine, and no bogeys.
He ended one stroke ahead of Kurt Kitayama of the U.S., who won the Mauritius Open last weekend, and surprise challenger Madalitso Muthiya of Zambia.
Zander Lombard was fourth on 64 while Ernie Els, a five-time winner of the event, opened with a 5-under 66.
Els, 49, had a run of five birdies in six holes from the seventh. His last victory at the South African Open was in 2010, and his previous win anywhere on the European Tour came in 2013.
The tournament is being played on the Firethorn Course and the Bushwillow Course. Players will have a round on each before the final 36 holes are held at Firethorn.