'It's difficult to explain,' said Fernandez-Castano. 'I went out today to play my best golf, and that's what happened. It's a dream come true. It's the icing on the cake.'
Gary Emerson, the overnight leader, struggled with the driver on Sunday. He two-putted for birdie at the last to polish off an even-par 70 and finish alone in second at minus-9.
Paul Broadhurst, who was tied with Fernandez-Castano one shot behind Emerson at the start of the final round, also shot an even-par 70. He took third at 8-under-par 272.
The lead turned quickly Sunday as Fernandez-Castano bogeyed his first, but rebounded with a birdie at No. 2. On the par-four third, Fernandez-Castano hit a 7-iron from 145 yards and dunked it for an eagle-2. That gave him the lead, one he did not relinquish, at 10 under par.
'I had about 145 yards to the pin and I tried to pitch it a few yards short of that,' admitted Fernandez-Castano. 'It just went in. I can't complain.'
Emerson only trailed by a shot and holed a nice 10-foot par save at seven. He knocked his approach inside 10 feet at the eighth, while Fernandez-Castano had close to 30 feet. The Spaniard drained his long putt, but Emerson ran home his putt to stay within one.
The ninth proved to be a critical hole. Emerson drove into the trees on the right, but had an opening that allowed him to play his second just short of the green. Fernandez-Castano hit his approach to 25 feet and Emerson played his third 3 feet short of the hole. Fernandez-Castano sank another long birdie putt and Emerson missed his to fall three behind.
Emerson bogeyed the 10th to drift four back, but last year's Russian Open winner had one trick left up his sleeve.
Emerson, who holed out for eagle at the first on Saturday, made eagle at No. 12 in the third round. On Sunday, he hit a 4-iron through the green and appeared to be in trouble considering Fernandez-Castano was 35 feet from the cup in two. Emerson chipped in for another eagle, and Fernandez-Castano three-putted for par.
While Fernandez-Castano holed the long birdie putts, and a 20-foot par save at 11, his flat stick let him down again at 14. He missed a 5-footer for par at the hole, but the lead stayed at two because Emerson made a mess of 14. Emerson, who missed the fairway with his drive, then again with his pitch-out, made bogey and was running out of holes.
Emerson badly pulled his tee ball left at the par-4 16th and landed in a right greenside bunker with his second. Fernandez-Castano found a fairway trap off the tee, but his second landed just long of the green. Emerson did not get up and down for par, but Fernandez-Castano did, and the margin was three with two holes to go.
Both parred 17 and Fernandez-Castano drove into trouble at the par-5 closing hole. He chipped out with his second and before he hit No. 3, Emerson hit a tremendous second that stopped 30 feet from the stick. Fernandez-Castano played his third into a greenside bunker.
Fernandez-Castano blasted out to 3 feet and Emerson nearly holed the eagle putt and tapped in for birdie. Had he made the eagle, that would have forced the tour rookie to make the putt to avoid a playoff.
It did not matter as Fernandez-Castano rolled in the par putt to become the seventh first-time winner on the European Tour in the 2005 campaign. He collected his first tour victory after only turning professional in September of last year. Fernandez-Castano was worried about retaining his card this year, now he has a two-year exemption.
'I was just one of those days where everything came easy,' said Fernandez- Castano. 'I was really feeling the pressure. I love this and think it will be good fun.'
Markus Brier shot a 1-under 69 and tied for fourth place with 2003 winner Maarten Lafeber, who posted a 2-under 68 on Sunday. The duo finished at 7-under-par 273.
Robert Coles fired a 4-under 66 to take a solo sixth at minus-6, while John Bickerton (65) and Peter Senior (70) shared seventh at 5-under-par 275.
David Lynn, last year's winner, carded an even-par 70 and tied for ninth with Pierre Fulke (68), Damien McGrane (68), Steven O'Hara (70), Andrew Oldcorn (71), Johan Skold (67) and Alessandro Tadini (72). The group was knotted at 3-under-par 277.