Spaniard Carlos Del Moral knocked two strokes off his previous best European Tour round and was in control of the Madeira Islands Open on Saturday night.
The 26-year-old from Valencia, with a previous highest finish on the circuit of fifth, charged from five behind to three in front with a sparkling nine-under-par 63.
Del Moral, ranked 397th in the world, reached 17 under par on a day to forget for former Ryder Cup player Oliver Wilson.
Hoping for his first victory after an amazing nine runners-up finishes, Wilson led at halfway, but managed only a 72 and is now four back in joint third.
Joakim Lagergren is second on 14 under following a 70, with his fellow Swedes Mikael Lundberg and Magnus Carlsson, Wilson and Portugal's Ricardo Santos one further back.
Del Moral took over at the top with six birdies in an outward 30 and then finished with three more birdies to march clear of the field.
Wilson did not have a single bogey in opening with rounds of 66 and 65, but mixed three with three birdies, the last of those on the final green at least boosting his confidence entering the final day.
Del Moral had just 22 putts in his round and told the European Tour website: "It was incredible.
"I putted beautifully and it gives me a lot of confidence. I had nine holes in a row - the entire front nine - with only one putt. And the ones that I missed were so close to going in.
"It was tough mentally on the back nine. I have been working on my swing for a while and this is the first time I've been up there in a tournament and it feels like it is in place.
"Last week at the Spanish Open I played well, but didn't putt well.
"I'm very excited about tomorrow. I've been up there before a few times and didn't perform as well as I'd hoped, but I'm a much more mature player now and I am looking forward to it."
Tour rookie Lagergren said: "I was a little nervous on the first tee, but that soon went away. My putter was ice cold and I missed a few short ones.
"I'll have to go on the hunt tomorrow. I've shot 66 the first two rounds, so I know there are low scores out there.
"Carlos is three ahead but that's not a lot in a final round, so I've just got to concentrate on playing well and hopefully I can catch him."
Collated third round scores & totals in the European Tour Madeira Islands Open, Santo da Serra, Madeira, Portugal
(Gbr & Irl unless stated, par 72):
199 Carlos Del Moral (Spa) 69 67 63
202 Joakim Lagergren (Swe) 66 66 70
203 Mikael Lundberg (Swe) 69 70 64, Magnus A Carlsson (Swe) 66 66 71, Oliver Wilson 66 65 72, Ricardo Santos (Por) 68 67 68
204 Richard Bland 68 67 69, Sihwan Kim (Nor) 68 66 70, Andreas Harto (Den) 67 71 66
205 Charlie Ford 67 68 70, Knut Borsheim (Nor) 68 69 68
206 Gary Orr 69 69 68, John Parry 71 70 65, Shiv Kapur (Ind) 70 68 68, David Dixon 68 68 70, Matthew Baldwin 67 70 69
207 Thomas Norret (Den) 69 68 70, Hans Peter Bacher (Aut) 67 69 71, Alastair Forsyth 69 68 70, Julien Guerrier (Fra) 70 69 68, Chris Paisley 69 69 69
208 Alex Haindl (Rsa) 69 68 71, Alvaro Velasco (Spa) 64 72 72, Adam Gee 68 71 69, Nick Dougherty 69 71 68, Andy Sullivan 68 64 76, Daniel Denison 70 71 67, Alessandro Tadini (Ita) 70 68 70, Tommy Fleetwood 66 70 72, Christopher Doak 70 68 70
209 Jordi Garcia (Spa) 72 66 71, Roope Kakko (Fin) 70 69 70, James Heath 69 69 71, Morten Orum Madsen (Den) 66 69 74, Ben Parker 66 72 71
210 Bjorn Akesson (Swe) 73 68 69, Jarmo Sandelin (Swe) 70 67 73, Warren Abery (Rsa) 67 72 71, Johan Wahlqvist (Swe) 70 70 70, Lloyd Kennedy 71 65 74, Raymond Russell 71 70 69, Emiliano Grillo (Arg) 73 68 69, Tyrone Ferreira (Rsa) 74 66 70, Pedro Oriol (Spa) 69 70 71
211 Joachim B Hansen (Den) 70 70 71, Jamie McLeary 69 69 73, Lasse Jensen (Den) 71 69 71, Stephen Dodd 73 68 70, Victor Riu (Fra) 72 69 70
212 Andrew McArthur 70 68 74, Sion E Bebb 69 69 74, Niclas Fasth (Swe) 73 68 71, Florian Praegant (Aut) 73 68 71, Benjamin Hebert (Fra) 70 69 73, Steven Tiley 71 69 72, Charles-edouard Russo (Fra) 74 66 72, Chris Lloyd 74 67 71
213 Nuno Henriques (Por) 73 67 73, Andre Bossert (Swi) 69 72 72, Markus Brier (Aut) 69 72 72, Antonio Rosado (Por) 72 69 72, Lloyd Saltman 68 73 72
215 Sam Walker 69 72 74, Steven Jeppesen (Swe) 73 68 74, Jean-Francois Lucquin (Fra) 73 68 74, Andrea Perrino (Ita) 70 71 74
216 Anthony Snobeck (Fra) 70 71 75
217 Jamie Elson 70 70 77
218 Maarten Lafeber (Ned) 71 70 77
220 Tim Sluiter (Ned) 69 71 80
