Rory McIlroy stayed close to the leaders at the SA Open on Friday despite hurting his back.
The second-ranked Northern Irishman (68) made five birdies on the first six holes of the back nine but bogeyed the final two to finish in a five-way tie for fifth after two rounds.
"I'm actually surprised I'm standing here. I actually thought about pulling out before even teeing off today," McIlroy said. "I tweaked my back somehow and the first few shots today weren't very comfortable and it still isn't really comfortable. I can't really take a deep breath because I've done something to my upper back."
McIlroy said he was going to get treatment in an effort to stay in the tournament.
Graeme Storm jumped into a two-stroke lead at the top of the leaderboard after shooting a course record 9-under 63 at the Glendower Golf Club.
Storm had nine biridies and leads Peter Uihlein (64), overnight leader Trevor Fisher Jr. (68) and Jbe Kruger (67) by two.
"I tip Rory to win this week because he hits it miles and he hits it straight," said Storm, who leads at 12-under 132 overall. "If I keep on his tail, I'll be happy."
Play was suspended at about 5 p.m. local time because of the threat of lightning, forcing several players to complete their second rounds on Saturday.
McIlroy, a stroke off the lead overnight, bogeyed the 17th when his putt for par rolled just left of the hole. He ended up in the bunker on the final hole and over-hit his escape shot. It left him with him a long but straight putt for par and his attempt fell just short.
McIlroy is playing this week as a favor to Ernie Els, the South African great and tournament host.