England’s Fleetwood looked set to lead on his own after six birdies and an eagle in his first 16 holes, but dropped his third shot of the day on the 18th to card a five-under-par 67.
At 16 under par he shares top spot with Argentina’s Ricardo Gonzalez, with Sweden’s Fredrik Andersson Hed a shot behind after a 66 on the Centenary Course which will host next year’s Ryder Cup.
“The last hole does not really mean anything,” Fleetwood said. “It’s a tough hole and the way I hit my tee shot I did well to make six. I carved it into the trees and was lucky to have a chip out.
“If I hadn’t I would have had to go back 100 yards and could have taken anything up to a 10. The way I played the first 17 holes was fantastic.
“I have been up there a bit this year and faltered a bit, so it’s nice that I have kept my good golf going for three rounds.”
Fleetwood was the youngest winner of the Challenge Tour in 2011, but only kept his card at the end of his rookie season on the European Tour thanks to a first top 10 of the year in the final event in South Africa.
The 22-year-old from Southport added: “I came off the Challenge Tour feeling I was the best golfer in the world, it felt very easy and I could not do much wrong. Last year I was still working hard but maybe not working on the right things.
“The more you play poorly out here, the easier it is to get into a downward spiral. It was horrible, I didn’t know that many people and it was very hard.
“At this tournament last year I’m not sure that I expected to be back on this tour this season, but I played great the second half of the season and have carried it on.
“This is what you spend hours and hours practising for, to be up there in golf tournaments. I always used to watch this tournament as a kid and I love Scotland. My parents, Sue and Pete, would move here in a heartbeat and we’ve got a house behind the 12th hole this week so I’ll do some practice and walk home.”
Gonzalez took a one-shot lead into the third round after back-to-back 65s but was only able to manage a 70 on Saturday, despite recovering from a bogey on the first with birdies at the second, fourth and ninth.
The 42-year-old’s last European Tour win came in 2009 but his mind has understandably been elsewhere recently after his mother, father and father-in-law all passed away in the space of the last two years.
“The last two years have been very difficult personally,” said Gonzalez. “If I win I would like to dedicate it to my mother and father, that’s my target this week.”
Scotland’s Stephen Gallacher is just three off the lead alongside Austria’s Bernd Wiesberger after charging through the field with a superb 64, despite continuing to struggle with a “freak” injury which threatened his participation.
Gallacher injured his back when washing his car on Monday and has been receiving treatment all week, but still stormed home in 30 and said: “A 64 is very good considering I didn’t have a warm-up.
“I hit two shots and had to go back in for more physio. The boys in the physio truck have been brilliant all week. They put a heat pack on it and gave me some tablets and said as long as I wasn’t having pins and needles it was just a strain and I couldn’t do any more damage.
“It’s one of those ones that eases off, sitting is horrific. By the time I come up here in the car it takes me about five minutes to straighten up. It was a freak injury, very bizarre, but my son and my nephew will take over cleaning duties from now on.
“If it had been any other place I would probably not have played, but I love this place and the course is set up perfect. The greens are fantastic and it’s a course where I have had a few low scores.”