Lee had six birdies and three bogeys Friday for a 3-under 68 and 5-under 137 total in windy and wet conditions. His Italian rival carded a 2-under 69 with three birdies and one bogey.
Perrino is leading a European Tour event for the first time of his career.
“I’ve just got to stay calm and make the best out it,” he said. “I’m not going to worry about it or play with fear, it’s just a game.”
Coetzee, who led by two shots after the first round, lost his lead with a bogey at the fourth and a double bogey at the 14th.