The Englishman’s bogey-free round included two birdies and an eagle on the par-5 12th hole, giving him a 9-under total of 133 as he looks for only his second European Tour title.
“I have played great for the last two days so they have been relatively easy,” Wall said. “This is a tough golf course and I have played really well again today.”
Wall attributed his success to an improved short game.
“I have just been looking at the low side of every putt for the last two days,” he said. “I’m really concentrating on the last third of the putt as opposed to the whole putt and that has definitely helped me. I haven’t holed everything but I have hit my putts a lot better.
“I haven’t really had a tough par putt for the last two days and that tells you how well I have been playing. If I can stay strong mentally then I should have a good chance to win here.”
Richard Green of Australia and France’s Raphael Jacquelin were tied for second, two shots back.
Green hit six birdies in his round of 67, but a double bogey at the 10th kept him from challenging for the lead.
Jacquelin didn’t drop a shot until the sixth when he shot a double bogey – his only sub-par hole.
Overnight joint-leader Stephen Dodd slipped into fourth with a 72 and is level with Sweden’s Oscar Floren, Paraguay’s Fabrizio Zanotti, Spain’s Alejandro Canizares and England’s Chris Wood on 137.
Colin Montgomerie, the former European Ryder Cup captain, appears on course for his best finish since leading Europe to glory last year. He was bogey-free on his way to a 69 to leave him in joint ninth with a 4-under 138.