The 24-year-old Schwartzel shot a 6-under 66 to total 6-under 210 at The Belfry. He was among the 24 players who completed the round before it was halted.
Schwartzel had a 29 on the front nine, but the two-time European Tour winner double-bogeyed his 13th hole.
It was an unbelievable front nine and I made a lot of putts and seven birdies very quickly, Schwartzel said. Then on my back nine, I felt like I played actually pretty much the same as I did on the front side, but I just drew a bad lie on my 13th and walked off with a double (bogey).
But other than that, it was actually a pretty solid round.
Fog delayed play more than three hours on Friday, and also caused a shorter stoppage early Saturday.
Englands Lee Westwood and Swedens Alexander Noren led at 6-under after the second round was completed Saturday morning. They didnt start their third round until 4 p.m. local time, with Westwood bogeying his opening three holes.
The six-time Ryder Cup star eagled his eighth hole and then birdied his 10th to get back to 6 under.
Swedens Mikael Lundberg, New Zealands Michael Campbell and Spains Alexandra Canisters were at 7 under but didnt complete their rounds.
Lundberg managed to pick up five shots in the 14 holes he played, while Campbell, seeking a first stroke-play success since winning the 2005 U.S. Open, had also picked up five strokes.
Canisters picked up two strokes through 10 holes.
Westwood, who is trying to defend the title and get his first victory this season, started struggling at the short 10th hole.
He hit a 5-wood off the tee that found the water guarding the green, taking the first of three straight bogeys. But the Englishman managed to regroup when he chipped in from a grenade bunker for an eagle at his eighth hole.
Westwood was critical of a decision to send the leaders off from No. 10, a move that had been sought by BBC TV.
It was done for TV and I was puzzled because when you are leading you expect to go off the first, but if it was done for TV then thats that, he said. TV is an important part of professional golf.
I would have rather started from the other side, but its not the reason I made those bogeys. Anyway, I have made a decent recovery and I could have played my way out of it but I managed to stay in there.