ST OMER, June 14, 2013 (AFP) - Overnight leader van der Walt was set to go into the weekend heading the pack only for three bogeys in the closing seven holes to bring him back level with Dinwoodie.
The Londoner put himself in contention with a faultess five under par 66 for a combined total of 138.
"Considering 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, it was great," the 30-year-old said.
"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."
One shot behind the leading pair were British duo Simon Wakefield and Chris Hanson and France's Victor Rui.
Leading second round scores at the St Omer Open on Friday (GBR & IRL unless stated, par 71):
138 - Tjaart Van Der Walt (Rsa) 67 71, Robert Dinwiddie 72 66
139 - Chris Hanson 71 68, Victor Riu (FRA) 68 71, Simon Wakefield 71 68
140 - Daniel Vancsik (ARG) 73 67, Jeppe Huldahl (DEN) 73 67, Daniel Gaunt (AUS) 70 70, Baptiste Chapellan (FRA) 72 68, Daniel Brooks 69 71, Justin Walters (RSA) 71 69, Seve Benson 75 65
141 - Jordi Garcia Pinto (ESP) 73 68, Scott Henry 72 69, Chris Lloyd 73 68
142 - Tyrrell Hatton 75 67, Andrew Marshall 74 68, Richard McEvoy 71 71, Thomas Fournier (FRA) 71 71, Luke Goddard 75 67, Benjamin Hebert (FRA) 74 68, Max
Glauert (GER) 77 65