The 29-year-old birdied four of his last five holes in a five-under 66 to move clear of the field with a 10-under-par aggregate of 132.
Ramsay, who heads a chasing pack made up of Finland's Jaakko Makitalo and Thai duo Panuphol Pittayarat and Chapchai Nirat, made 11 straight pars after an early birdie on the 11th – he started on the 10th – before he moved up the gears on the run-in with a profitable burst that was concluded with a tricky, downhill putt of 25-feet for a birdie on his last hole.
"The key was patience," said Ramsay. "I knew I was playing well and sooner or later would make something. It was nice to be rewarded on the last five holes."
At the ISPS Handa Perth International in Australia, Alastair Forsyth and Craig Lee both cemented their places in the top-15 with two-under 70s for four-under 140s.
The Scottish pair, who are battling to save their European Tour cards, sit four shots behind Argentinian pacesetter, Emiliano Grillo.
Scott Jamieson posted a 71 for 143 but George Murray, also fighting to keep his card, leaked three shots on his last six holes in a 71 and missed the cut by two on a 148.