Final round leaderboard:
-16 M Manassero (Ita) -12 I Garrido (Spa) -11 J Luiten (Ned), Peter Lawrie (Ire), G Boyd (Eng), C Nilsson (Swe)
Selected others: -8 G Orr (Sco), J Parry (Eng), R Finch (Eng), -6 O Wilson (Eng)
Manassero shot four rounds in the 60s to win the Castello Masters
Italian teenager Matteo Manassero has become the youngest European Tour event winner with a four-shot victory at the Castello Masters in Valencia.
The 17-year-old sank three consecutive birdie putts on the back nine to move to 16 under with a final-round 67.
Spain's Ignacio Garrido finished second on 12 under, while England's overnight leader Gary Boyd dropped four shots in three holes to end on 11 under.
"It feels fantastic. It's unbelievable, a very special moment," said Manassero.
"I couldn't imagine to be a winner the first year, it was just to keep my card and now I'm a winner already."
It was a stunning performance from the teenager who, at 17 years and 188 days, broke the record that had been held by New Zealander Danny Lee who was 18 years and 213 days old when he won the 2009 Johnnie Walker Classic.
The former British Amateur Champion, who made his professional debut at the Italian Open in May, also becomes the youngest full European Tour member as a result of this win, eclipsing the previous record held by Spain's Seve Ballesteros by just 12 days.
Manassero started the day two shots behind 24-year-old Tour rookie Boyd, who will have gone into Sunday's final round in confident mood having fired a course record-equalling 63 on Saturday.
And Boyd appeared to be coping well as leader, reaching the turn with his two-shot advantage still intact.
However, the Italian, whose only blemish was a bogey on the seventh when he missed a short putt for par, played wonderful golf on the back nine.
"The turning point was saving par on 12 and then hitting birdie on 13," Manassero added.
"I was very nervous at the beginning and very nervous at the end even with a good cushion of shots."
The nerves were not visible to those watching history being made though as he sank birdies on 13 and 14 to bring him level with Boyd before the big swing came on the 15th and 16th holes.
Manassero played the 15th in textbook fashion, with a solid drive and five iron before sinking a 20-foot birdie putt, while Boyd, who found a fairway bunker with his drive, left his approach from the sand short of the green. He also left his chip short before missing the par putt.
The screw was turned further on the par-three 16th when Manassero found the centre of the green with his tee shot and the Englishman buckled, dumping his iron shot into the water and eventually walking off with a double bogey.
And from being two shots in front with six to play, Boyd was four behind with two to play.
He then dropped a further shot on the 17th to slip to 11 under par and his final-round 74 left him in a tie for third.
Spaniard Garrido produced a solid bogey-free round which featured three birdies on the back nine to move up to second place on 12 under.
England's John Parry had been well in contention on 13 under after 14 holes but a disastrous final four holes, that saw him drop five shots, left him in a tie for 13th alongside Scotland's Gary Orr who moved up 15 places with a four-under-par 67.