It has been an up-and-down week for Lahiri, who will shift his focus to the PGA Tour after this event, as he has struggled to score on the back nine, where apart from six bogeys, he has also given away a double in the first round and a triple in the third.
However, the two patches of good scoring has been the front nine on first day, and the four-hole stretch on back nine last evening.
The Dane started the second day at Regnum Carya Golf & Spa Resort with a six-shot lead and while that was cut to four at one point, a late birdie burst meant he signed for a 68 and was in total control at 18 under.
Olesen is searching for a fourth European Tour win and a third in as many seasons after his victories at the ISPS HANDA Perth International and the Alfred Dunhill Links Championship.
There was then a group of five players at 11 under with David Horsey, Li Haotong, David Lipsky, Matteo Manassero and Bernd Wiesberger all searching for a low one on Sunday.