The Scot, who is three shots behind leader Paul Wesselingh, who also shot a 66, reached the turn in five-under-par 31 for a second consecutive day courtesy of three birdies in the first four holes and an eagle on the sixth, when he holed a 20-foot putt.
Having faltered on the back nine in the first round, when he followed a bogey on the 13th with a double bogey on the 14th, the Scot appeared to struggle in the heat once more, dropping his first shot of the day on the 15th hole when he missed the green and failed to get up and down.
However, he finished his round on a high with back-to-back birdies, holing consecutive putts from 20ft on the 17th and 18th holes to move to eight under par.
"It was great to have a two-four finish as I've not played the back nine very well at all," he said. "Fatigue does play a factor at the end in this heat, but the back nine does play tighter than the front too. Yesterday, I lost concentration and the three putt on the last when I had a 12 foot putt for eagle was crazy. But I've given myself a chance.
"If I play the back nine well tomorrow I have a decent chance, but Paul is playing particularly well. If I can get off to a flying start, the way I have the first two days, then I can put some pressure on him."
Wesselingh is on course to finish the season as Senior Tour No 1 after scoring six birdies to move to 11-under-par 133. Last year's Order of Merit winner, Roger Chapman (72), and South African Hendrik Buhrmann (69) share third position on five under par.