SAINT-OMER, France --
The Englishman had a bogey-free round to join Van der Walt (71), the overnight leader, at 4-under 138. Dinwiddie also led after the second round of the 2010 Saint-Omer Open, finishing second that year.
"I know the course very well and I have a lot of good feelings around here," Dinwiddie said. "I did not think I would be leading after the afternoon but I knew I was in a good position no matter what.
"I didn't think I would be teeing it up after taking a bad step on Tuesday morning and damaging a bad disc in my back. I couldn't hit a ball on Wednesday, so I honestly thought I had no chance. But I just iced it and took a lot of anti-inflammatories and recovered. So it was great."
Van der Walt moved three strokes ahead of Dinwiddie at one stage, but three bogeys on the back nine hurt the South African.
"I didn't hit bad shots, but my chipping around the greens was not great and all my bogeys were from next to the green," Van der Walt said. "I'm disappointed but I'm still in there and I was shocked walking up 18 to see I was still top."