Branden Grace shot a 5-under 67 and extended his lead to five shots after the second round of the Dunhill Links Championships on Friday.
Grace credited a practice round with British Open winner and fellow South African Louis Oosthuizen for helping him improve to 17 under.
''Louis gave me some lines off the tee which was very helpful, especially with the wind off the left,'' he said. ''The first six holes are not the easiest driving holes out there. Having Zach (Rasego), who caddied for Louis when he won the Open, also helped.
Grace teed up on the Old Course, where Oosthuizen won golf's oldest major two years ago. He birdied four straight holes mid-round to add to his opening-day record 60 at Kingsbarns.
Joel Sjoholm of Sweden, in his first competitive round on the Old Course, matched Grace's score of 67 to move into second at 12 under, tied with Thorbjorn Olesen of Denmark (69).
Grace created a sensation at the start of the year on the European Tour, winning three events before May. He struggled after that, but arrived in Scotland having won the Vodacom Origins of Golf Final at Fancount last week on the South African Sunshine Tour.
Martin Kaymer was the best finisher of the four competing Ryder Cup players with a 71 at Kingsbarns to move to 3 under. Peter Hanson (70) was a stroke back, American Dustin Johnson shot 71 for 1 under and Paul Lawrie (70) was 1 over.
''It has been a little difficult to get motivated,'' Kaymer said. ''I had that fantastic experience on Sunday, and I'm still very inspired. But on the other hand your body is just a little tired, and you have to listen to your body.''
Former champion Colin Montgomerie (70), British Open champion Ernie Els (70) and two-time champion Padraig Harrington (73) were well behind the leader.
