Neither co-leader had a bogey Thursday while playing the West Course of the Royal Johannesburg and Kensington Golf Club. They move to the East Course for their remaining rounds.
The tournament is contested on the East and West courses until after the second-round when the rest of the event is on the par-72 East Course.
Bryce Easton had a hole-on-one on the 200-yard 12th hole in turning in a 7-under 65 for the best score of the day on the East Course. He had a birdie on the sixth hole and finished each nine with back-to-back birdies.
Eight players are tied for fourth at 6-under.
Sterne opened his round with three straight birdies and added a birdie at the par-3 eighth before chipping in for eagle at the par-5 ninth hole. He got to 8-under with birdies at 13 and 15.
Kieffer had four sets of back-to-back birdies. His first came at Nos. 2 and 3 with another at 6 and 7. He made the turn at 5-under after a birdie at the ninth hole and opened his second nine with a birdie at 10. He tied Sterne with birdies at 15 and 16.