Chawalit Plaphol, who held at least a share of the lead after each of the first two rounds, struggled to a 2-over 74. He was joined in a tie for second place at 10-under-par 206 by Oliver Wilson. Wilson, who played with Plapohl, managed one birdie and 17 pars for a 71 at Shenzhen Golf Club.
Asian Tour veteran Lian-Wei Zhang fired a 6-under 66 to move into fourth place at minus-nine. Soren Kjeldsen and Barry Lane each notched rounds of 5-under 67 to climb into a tie for fifth at 8-under-par 208. They were joined there by Miles Tunnicliff, who carded a 2-under 70 on Saturday.
Fisher, who is playing in just 11th European Tour event, got off to a slow start with a bogey on the second. He got that stroke back as he birdied the par-3 fifth.
The Englishman birdied the eighth for the third straight round, but faltered to a bogey at the next to turn at seven-under. Fisher caught fire on the back nine. He birdied the par-5 12th for the third round in a row.
Fisher, whose best finish on tour was a tie for sixth at the 2005 Aa St. Omer Open, moved to minus-9 with a birdie on the par-4 14th.
The 25-year-old ran in a long birdie putt on the 16th to grab a share of the lead. Fisher came right back with a 12-foot birdie putt on 17 to take the outright lead. He parred the last to remain there.
'This is very uncharted territory,' admitted Fisher. 'I played a few tour events last season, which has been a massive help to me, just to be out there competing with the big boys. I've won a few events, but I don't think anything can compare to this. It was pretty cool to see my name on the leaderboard Friday when I finished and to see it on top now is an awesome feeling.'
Plapohl struggled with his swing all day. He went bogey-birdie-bogey-birdie from the third before things took a turn for the worse. At the seventh, his drive stopped against a tree and he was forced to pitch out.
The Thailand native came up short with his third. Plapohl pitched within 7 feet, but could only two-putt for a double bogey that dropped him to 10 under. Plapohl found the fairway off the tee at the par-5 eighth, but sent his second shot well right of the green and into the water.
After taking his drop and knocking his fourth shot onto the putting surface, Plapohl two-putted for bogey. That dropped him to 9 under and a share of the lead with Wilson.
Plapohl steadied himself with three straight pars from the ninth. He got up and down for birdie at the par-5 12th to move back into the lead at minus-10. Plapohl could only par his final six holes to end one shot back.
'I just drove the ball badly all day,' Plapohl said. 'On the practice range, the swing didn't feel good and I carried that into the round. It got a bit better on the back nine and I managed to play a bit better. At least that kept me just one off the lead.'
Wilson seemed destine to post 18 pars during his round. He parred 15 consecutive holes to start the day. Finally on the par-3 16th, Wilson's 8-foot birdie putt curled into the cup as he moved to 10 under. He also parred the final two holes.
Gaurav Ghei carded a 5-under 67 to move to 7-under-par 209. He shares eighth place with Peter Lawrie, Jyoti Randhawa, Fredrik Widmark, Francois Delamontagne, Anders Hansen and Shiv Kapur.
Paul Casey and Kenneth Ferrie are among a group of five players one stroke further back at minus-6.