Ricardo Santos shot a spectacular closing 63 to give Portugal their first European Tour win for 20 years.
The 29-year-old turned a four-stroke deficit into a stunning four-shot victory on home soil at the Madeira Islands Open.
"It is very emotional and I haven't got the words to describe how I feel," world number 306 Santos told the European Tour website after grabbing five birdies in the last seven holes.
"To win my first European Tour event in my own country is very special.
"It was a sensational round, definitely the best of my career. It was amazing to have the crowds here supporting me and it would be difficult to imagine a better win than this.
"I didn't have many bad moments in the round, but the supporters were always there to pick me up and keep me going.
"This is a huge moment in my career."
Swede Magnus Carlsson was second and Dane Andreas Harto third as Spaniard Carlos Del Moral, three clear at the start of the day, fell away to joint fourth with a 73.Daniel Silva was Portugal's last champion on the circuit at the 1992 Jersey Open.
Jose-Filipe Lima, winner of the 2004 St Omer Open, is now Portuguese, but played under the French flag when he took that title.
Del Moral threw the race for the title wide open by following a bogey on the short eighth with a triple bogey at the 385-yard next.
Harto looked set to be the one to take advantage, taking over top spot after a brilliant front nine 30. But he then had three bogeys in four holes from the 12th.
Santos, a graduate from last season's Challenge Tour whose previous best finish on the circuit was 10th, sank a monster putt on the 17th to all but guarantee victory and then put the icing on the came with another birdie at the last.
Harto said: "The front nine was incredible - I holed some really, really long putts. Unfortunately I just couldn't keep it going and missed some short ones.
"There was a point where I saw a leaderboard and saw I was in front. It's hard not to think about winning.
"I tried to put it out of my head and just concentrate on playing the next shot.
"But this is a great week for me - there are many positives to take from this."
It is the second week running someone has won from four back after 54 holes. Francesco Molinari did it at the Spanish Open.
Collated final round scores and totals, Santo da Serra, Madeira, Portugal
(Gbr & Irl unless stated, par 72):
266 Ricardo Santos (Por) 68 67 68 63
270 Magnus A Carlsson (Swe) 66 66 71 67
271 Andreas Harto (Den) 67 71 66 67
272 Carlos Del Moral (Spa) 69 67 63 73, Mikael Lundberg (Swe) 69 70 64 69, John Parry 71 70 65 66, Oliver Wilson 66 65 72 69, Joakim Lagergren (Swe) 66 66 70 70
273 David Dixon 68 68 70 67, Alastair Forsyth 69 68 70 66
275 Sihwan Kim (Nor) 68 66 70 71, Gary Orr 69 69 68 69, Hans Peter Bacher (Aut) 67 69 71 68, Julien Guerrier (Fra) 70 69 68 68, Morten Orum Madsen (Den) 66 69 74 66
276 Richard Bland 68 67 69 72, Alex Haindl (Rsa) 69 68 71 68, Andy Sullivan 68 64 76 68, Charlie Ford 67 68 70 71, Ben Parker 66 72 71 67, Christopher Doak 70 68 70 68
277 Alessandro Tadini (Ita) 70 68 70 69, Victor Riu (Fra) 72 69 70 66, Matthew Baldwin 67 70 69 71, Chris Paisley 69 69 69 70
278 Shiv Kapur (Ind) 70 68 68 72, Knut Borsheim (Nor) 68 69 68 73
279 Thomas Norret (Den) 69 68 70 72, Daniel Denison 70 71 67 71, Alvaro Velasco (Spa) 64 72 72 71, Tyrone Ferreira (Rsa) 74 66 70 69, Lloyd Saltman 68 73 72 66
280 Jordi Garcia (Spa) 72 66 71 71, James Heath 69 69 71 71, Niclas Fasth (Swe) 73 68 71 68, Jarmo Sandelin (Swe) 70 67 73 70, Nick Dougherty 69 71 68 72, Johan Wahlqvist (Swe) 70 70 70 70
281 Emiliano Grillo (Arg) 73 68 69 71, Jamie McLeary 69 69 73 70, Stephen Dodd 73 68 70 70, Warren Abery (Rsa) 67 72 71 71
282 Andrew McArthur 70 68 74 70, Adam Gee 68 71 69 74, Lloyd Kennedy 71 65 74 72, Raymond Russell 71 70 69 72
283 Joachim B Hansen (Den) 70 70 71 72, Lasse Jensen (Den) 71 69 71 72, Florian Praegant (Aut) 73 68 71 71, Pedro Oriol (Spa) 69 70 71 73
284 Bjorn Akesson (Swe) 73 68 69 74, Tommy Fleetwood 66 70 72 76
285 Sam Walker 69 72 74 70, Andre Bossert (Swi) 69 72 72 72, Nuno Henriques (Por) 73 67 73 72, Jean-Francois Lucquin (Fra) 73 68 74 70, Charles-edouard Russo (Fra) 74 66 72 73, Benjamin Hebert (Fra) 70 69 73 73, Chris Lloyd 74 67 71 73
286 Roope Kakko (Fin) 70 69 70 77, Markus Brier (Aut) 69 72 72 73, Antonio Rosado (Por) 72 69 72 73
287 Sion E Bebb 69 69 74 75, Anthony Snobeck (Fra) 70 71 75 71
288 Tim Sluiter (Ned) 69 71 80 68, Andrea Perrino (Ita) 70 71 74 73
289 Steven Tiley 71 69 72 77
290 Jamie Elson 70 70 77 73, Steven Jeppesen (Swe) 73 68 74 75
292 Maarten Lafeber (Ned) 71 70 77 74
