Els shot 5-under-par 67 on a soggy day at the Gary Player Golf Club to take a one-shot lead over fellow South African Retief Goosen, Mike Weir, 1996 champion Colin Montgomerie, two-time winners Bernhard Langer and Nick Price, and Sergio Garcia.
Garcia could have been tied for the lead had it not been from a bout of dizziness at the par-5 ninth. The 21-year-old Spaniard repeatedly backed away from his 2-iron approach shot to the island green from what he called a bout of sea sickness.
I stepped away because I was dizzy and couldnt concentrate, Garcia said. The ball looked like it was moving.
Els had no such problems on Thursday, but admitted he was surprised to be leading.
I started off a bit tight, said the two-time defending champion. The rain didn't allow me to get into a rhythm on the practice range, but I hit a good wedge on the first and then two good shots to birdie the second, too. In fact, I could have been 7-under after the first seven holes.
Lee Westwood, who lost to Els in a playoff last year, is two back after shooting 69. Despite making a triple-bogey 7 at the par-4 eighth, Padraig Harrington birdied five of his next six holes to finish at 2-under 70.
Dane Thomas Bjorn and American Jim Furyk are tied for 10th place at 1-under, while Darren Clarke is the last of the 12-man field after a round of 3-over 75.
The winner will receive $2 million.