The 26-year-old played a flawless round with five birdies and no bogeys. After complaining about his putting in the first round, he appeared more satisfied with his performance heading into the weekend.
'I hit every green, like I did in the final round of the South African Open,' said Clark. 'I've got that level of concentration I had there. I missed it at the Dunhill Championship because, coming so soon after the South African Open, it's difficult to maintain that level of concentration.'
The Durban native notched his first European Tour win at the South African Open earlier this month. He earned his PGA Tour card after finishing third on the 2000 Buy.com money list.
A wrist injury forced Clark to miss most of the 2001 season. He will play the 2002 campaign under a medical exemption.
'When I was injured, I certainly didn't expect to be winning these events. But my game's obviously come around quite nicely,' he said.
Clark is scheduled to return to the PGA Tour at the Pebble Beach Pro-Am next week, although he remains uncertain he will make the trip due to his current lead in the Sunshine Tour Order of Merit.
'I haven't decided what I'm going to do yet,' he said. 'For now I'm just trying to win here, and hopefully that will seal the Order of Merit title for me. I just want to concentrate on the next two rounds, and I'll take it from there.'
A first-place finish in the Order of Merit would grant Clark an automatic entry into both the British Open and the World Golf Championship's World Match Play.
Don Gammon (68), Marco Gortana (68) and overnight co-leader Michael Kirk (70) are tied for second at eight-under 136.
Gammon made the cut at both the South African Open and the Dunhill Championship leading up to this event. The 31-year-old is eager to earn his first win on the Sunshine Tour this year.
'I'm just chipping away, hoping that one of these days I'll break through with a win,' he said.
A group of seven remained one-shot further back at 7-under 137, including overnight co-leaders Andrew McLardy (71) and American Bruce Vaughan (71).
England's Chris Williams had the low round of the day with a 64. He leads a group of eight knotted at 6-under 138.
Norman Mashada had an ace on the 221-yard 12th. The shot helped Mashada make the halfway cut which fell at 1-over 145.