“It was tough out there with the wind blowing. Most of these holes are tree-lined and it’s hard to trust the breeze, so I struggled with that on the back nine.
“I played some great golf today, but didn’t really make putts. It went pretty well through 10 holes and then maybe lost a bit of concentration, and that’s when you’ll let a few shots slip out there,” he said.
The world number 22 shot a record 63 opening score to lead on Thursday, but fell back into third place on Friday. He made the 36-hole mark on 10-under-par and four shots behind midway leader Kevin Kisner.
“I’m still up there, but it would be nice to have a couple of putts go in near the end,” said Grace. “I’m a few back and there’s a long weekend ahead.”
The 27-year-old has enjoyed a superb year that includes top-fives at the US Open and PGA Championship, along with a 5-0-0 result at The Presidents Cup.
This week he has played himself into a position where he can continue to make headlines.
“There are two rounds to go and you just want to be thereabouts. Tomorrow is moving day and we’ll try to get into a good position ahead of Sunday, so we’ll see what the tournament has in store for us,” he said.
Countryman Louis Oosthuizen reached the 18th tee box tied for third place on 10-under and then proceeded to make triple-bogey seven. The 2010 Open Champion fell back into a share of ninth on seven-under, but has 36 holes to make his comeback.
Charl Schwartzel carded 72 on Friday to take up a share of 27th place, while Trevor Fisher Jnr and Thomas Aiken were part of a 10-way tie for 37th place.