ABU DHABI, 18 Jan, 2015 (AFP) - Kaymer, a two-time major winner and ranked 12 in the world, increased his advantage over the field to 10 shots after five holes on Sunday, before the implosion.
A double bogey on the par-4 ninth hole by the German was followed by a triple bogey seven on the par-4 13th.
And while the birdies completely dried up for Kaymer, 22-year-old Stal, who started the day eight shots behind the leader, raced into the lead with six birdies in his first 11 holes.
He dropped his most crucial birdie putt from 20 feet on the par-4 16th hole that gave him a two-shot cushion over Kaymer and world number one Rory McIlroy.
McIlroy (66) almost holed his bunker shot on the 18th hole for an eagle, but could only manage a birdie that secured him second place ahead of Kaymer at 18-under par 270.
Playing one group behind McIlroy and one ahead of Kaymer, Stal then had the luxury to make a par for a bogey-free round of seven-under par 65 and a winning tally of 19-under par 269.
Kaymer finished third at 271, with Stal’s compatriot and world number 19 Victor Dubuisson and Belgium’s Thomas Pieters tying for fourth at 272.
Stal’s victory earns him a three-year-exemption on the European Tour and could move him to just inside the top-100 of the world rankings when they are released Monday.
It also takes him to number three on the Race to Dubai points list.
A two-time winner on the Challenge Tour in 2012, Stal choked up thinking of his mother Christine, who passed away last year when he was playing the BMW PGA Championship in May, and said: “It’s really crazy and I am very happy to win this tournament.
"It’s unbelievable to win, because when I saw the leaderboard on the fifth hole, I saw Martin Kaymer on 23‑under, and I said, it’s not possible to win.
"But when I saw the leaderboard on the 16th, I saw him at 17‑under. So, in my head, I say, it’s possible, you can do it.
"Obviously, my heartbeat went up, but I tried to stay focused on the next shot. I just wanted to continue to play the same way. And I did."
Kaymer joined a list of only three players who have lost a record lead of six shots on the final day on the European Tour.
"Yeah, surprised, a little shocked. I don’t really know how to put it into words," said 30-year-old Kaymer.
"It was very, very surprising today. Started off well and hit a couple bad tee shots and that cost me double‑bogey and a triple‑bogey.
"Twice I missed the grass and I was in a bush. Had to drop it in the sand. Obviously then you get a bad lie and then it’s tough to make bogey.
"I haven’t done that all week long. Unfortunately, I did today, and that cost me the tournament."
McIlroy rued the fact he could not make any headway on the third day Saturday, and for the first few holes on Sunday, before he asked his caddy JP Fitzgerald, to start reading the putting lines.
"I was told on the 15th tee that Martin had made triple on 13. So I knew with a good finish you never know what could happen," said McIlroy.
"I was pretty aware; the last sort of four or five holes, I knew I was in there with a chance.
"I think Martin was ten ahead at one point. You think from there, there’s only one winner, but just shows you, funny things can happen in this game. If you just sort of plug away and stay patient, your time will come. But just a little too late for me today."
Complete fourth-round scores in the $2.7million Abu Dhabi Golf Championship on Sunday at the par-72 Abu Dhabi Golf Club:
269 - Gary Stal (FRA) 68-69-67-65
270 - Rory McIlroy (NIR) 67-66-71-66
271 - Martin Kaymer (GER) 64-67-65-75
272 - Victor Dubuisson (FRA) 69-72-64-67, Thomas Pieters (BEL) 65-67-70-70
274 - James Morrison (ENG) 68-67-72-67, Tyrrell Hatton (ENG) 66-71-70-67, Bernd Wiesberger (AUT) 72-65-66-71
275 - Ross Fisher (ENG) 71-69-69-66, Jamie Donaldson (WAL) 73-67-65-70, Charl Schwartzel (RSA) 71-68-65-71
276 - Ernie Els (RSA) 70-72-69-65, Justin Rose (ENG) 73-69-69-65, Alejandro Canizares (ESP) 69-70-71-66, Oliver Fisher (ENG) 69-70-70-67, Steve Webster (ENG) 73-67-67-69, Anthony Wall (ENG) 70-71-66-69, An Byeong-hun (KOR) 67-75-65-69, Morten Orum Madsen (DEN) 68-69-69-70
277 - Paul Lawrie (SCO) 68-73-67-69, Niclas Fasth (SWE) 69-70-68-70, Branden Grace (RSA) 66-74-67-70, Miguel Angel Jimenez (ESP) 72-67-67-71, Dawie van der Walt (RSA) 70-70-65-72, Alexander Levy (FRA) 66-70-67-74
278 - Nicolas Colsaerts (BEL) 68-71-72-67, Maximillian Kieffer (GER) 70-71-68-69, Anders Hansen (DEN) 68-73-68-69, Richard Green (AUS) 68-68-71-71, Eddie Pepperell (ENG) 70-68-68-72
279 - Scott Hend (AUS) 70-70-70-69, Rafael Jacquelin (FRA) 69-71-69-70, YE Yang (KOR) 70-70-69-70, Mike Lorenzo-Vera (FRA) 69-69-71-70, Marcus Fraser (AUS) 72-68-67-72, Peter Uihlein (USA) 67-68-70-74
280 - Robert Rock (ENG) 69-73-70-68, Richard Sterne (RSA) 71-70-70-69, Jordi Garcia Pinto (ESP) 70-71-70-69, Alex Noren (SWE) 67-75-68-70, George Coetzee (RSA) 68-73-68-71, Emiliano Grillo (ARG) 70-70-68-72, Oliver Wilson (ENG) 71-71-66-72, Gregory Bourdy (FRA) 66-74-66-74
281 - Kiradech Aphibarnrat (THA) 72-67-72-70, Andrew Johnston (ENG) 73-68-70-70, Kristoffer Broberg (SWE) 69-71-70-71, Soren Hansen (DEN) 69-69-70-73, Robert Karlsson (SWE) 67-71-69-74,
282 - Thorbjorn Olesen (DEN) 72-69-72-68, Anirban Lahiri (IND) 72-68-72-70, Bradley Dredge (WAL) 72-70-70-70, Mikko Ilonen (FIN) 66-75-68-73
283 - Richard Bland (ENG) 69-73-72-69, Damien McGrane (IRE) 71-69-71-72, Seve Benson (ENG) 69-73-67-73,
284 - Oliver Farr (WAL) 73-69-72-70, Matthew Nixon (ENG) 68-71-74-71, Renato Paratore (ITA) 70-69-73-72, Danny Willett (ENG) 70-71-71-72, Craig Lee (SCO) 73-68-70-73, Andy Sullivan (ENG) 71-71-67-75
285 - Jorge Campillo (ESP) 72-70-77-66, Johan Carlsson (SWE) 70-72-71-72, Jeev Milkha Singh (IND) 68-73-71-73
286 - Rickie Fowler (USA) 67-75-73-71, David Drysdale (SCO) 70-71-74-71, Simon Khan (ENG) 73-67-72-74
288 - Jbe Kruger (RSA) 74-68-72-74
289 - Darren Fichardt (RSA) 69-73-77-70, Tian-lang Guan (Am-PRC) 70-69-78-72
290 - Jason Palmer (ENG) 71-71-76-72