Scotsman Forrest had led by one stroke at the halfway stage, but things started going wrong when he went bogey-par-bogey from the eighth on Saturday.
But three birdies in his final five holes, including two in a row to finish his third round, enabled Forrest to climb up to eight under par, three clear of Norway's Kristoffer Reitan, who carded the best round of the day with a 68, Englishman Todd Clements and Dutchman Daan Huizing.
Micheluzzi, who had hoped to really ignite his challenge as he began the day in joint-fifth place, could only record a disappointing 75 as he slipped to one over for the tournament, nine off the pace in 18th place.
"Well, there is a long way to go tomorrow," Forrest said. "Really happy with the way I dug in today and a lovely way to finish. It took a lot of patience, but yeah, see what tomorrow brings.
"I played nicely (over the) first seven holes. The bogey at the 10th actually felt like a boost because I was staring at a seven in the face, to escape with a six settled me down a little bit.
"I just kept on giving myself chances and finally got a couple of putts to drop.
"I'm pretty happy with my game plan so far, I've not checked what the weather's to be, but if it's similar conditions, it's hit fairways and greens - that old chestnut. I've done that pretty well so far and staying patient."
English pair Joe Dean and Andy Sullivan and Denmark's Jacob Skov Olesen all carded 70s to sit five shots off the lead in a share of fifth.
Australian Elvis Smylie, like Micheluzzi, had a 75 and is four-over for the tournament, tied for 31st, while Jason Scrivener recorded a 77 and is eight over for the week.
