Defending champion Charl Schwartzel of South Africa shot a 10-under 61 for a share of the halfway lead at the rain-affected Joburg Open on Friday.
Schwartzel had 10 birdies on the West Course at Royal Johannesburg and Kensington Golf Club to finish even with Jamie Elson of England and Garth Mulroy of South Africa at 13-under 129 after the second round.
Elson had five straight birdies in a 64 on the longer East Course. Mulroy also shot 64 on the East, mixing an eagle, seven birdies and two bogeys.
James Kingston shot a 62, Thomas Aiken had a 66 and Tyrone Mordt a 68 to be tied for fourth one shot back.
Players alternate courses over the first two days of the European and Sunshine Tour event before playing the final two rounds on the East Course.
Play was called off Friday because of fading light with a handful of players — including Welshman Stuart Manley — still playing. Manley was 9 under through 15 for a tie for 11th.
Schwartzel, the highest-ranked player in the tournament at 32, raced into contention for a successful title defense with five birdies either side of the turn for his 10-under round.
"It was a fantastic round today," Schwartzel said. "It really fell into place and I hit some great tee shots and iron shots, and I used just about every opportunity I had on the greens."
Elson birdied Nos. 5-9 and collected shots at the par-4 11th and par-5 18th to set the early pace on the tougher East Course, before Mulroy and Schwartzel joined him on 13 under.
The Englishman's front-nine run was interrupted by the weather, before he returned to pick up two more shots coming home.
"It's not ever nice to be stuck, especially when I had some momentum going," he said. "I hit a few balls on the range before the restart and my rhythm was all over the place, so it was great to make a birdie in the last two holes."
Aiken had an up and down second round, his eight birdies tempered by three bogeys to stay in a tie for fourth.
Kingston's 62 catapulted him 36 places up the leaderboard. He would have equaled Schwartzel's 61 on the West Course if not for a missed par putt on the last for his only dropped shot of the day.
Mordt, the co-overnight leader with fellow South African Martin Maritz, added a 68 on the East Course to his opening 62.
Maritz had bogeys on Nos. 14, 15, and 16, on the supposedly easier West Course, to slip from a tie for 1st to a share of seventh on 11 under with fellow South African Branden Grace.
Grace was one of the last players to finish his round and signed off in style with an eagle on the 551-yard par-5 18th on the East Course.