Brooks Koepka held off a spirited challenge from Ian Poulter to win the Turkish Airlines Open by the Ministry of Youth and Sports.
Koepka claimed his first European Tour title in Antalya, a result which ensured Rory McIlroy won The Race to Dubai for the second time in three years.
The American carded a flawless closing 65 at the Montgomerie Maxx Royal to finish 17 under par, one shot ahead of Poulter, who missed a birdie putt from six feet on the 18th to force a play-off.
Marcel Siem, Jamie Donaldson or Sergio Garcia had needed to win in Turkey and at next week's DP World Tour Championship to have a chance of overtaking McIlroy.
And although Siem started the final round just one shot off the lead, the BMW Masters winner could only card a closing 71 to finish joint eighth, with Donaldson 19th and Garcia 25th.
Koepka, who won three times on the Challenge Tour last year to gain instant promotion to The European Tour, carded four birdies on the front nine and holed from 40 feet for another on the 10th, before a brilliant approach to the 13th set up an eagle from just eight feet.
That gave him a two shot lead and although Poulter halved his deficit with his fifth birdie of the day on the same hole, the Ryder Cup star was unable to find another on the last despite a superb long greenside bunker shot.
“It's a special week obviously, these four events and The Race to Dubai are ones you prepare for all year, and to win one of them is very special,” said Koepka.
“I feel like I've been playing really well. I've been knocking on the door, and these last maybe two, three months, I've been very close over here and in the States - I felt like I should have won a couple.
“But I've been knocking on the door and I've learned something every time, and used that today. I was very relaxed, very calm today, and it showed I guess.
“To look where I was a year and a half ago on The Challenge Tour and now to be a winner on The European Tour is incredible, especially winning four times there and winning out here, it's very special. So I'm excited to get to next week and hopefully carry my form over.”
Poulter, who had a six-shot lead at halfway before a third round of 75, said: "Hats off to Brooks for a great round today, obviously he's played some superb golf there.
"The damage was done on Saturday. That, for me, is really disappointing. To have played three great rounds of golf, and just one blip on Saturday, which is a real shame.
"So you know, it's frustrating, is what it is. There's no other word for it. Yes, I'm going to be angry. I'll be angry for a good few days. But that's fine. I'll keep myself in my own little room and have a little chat with myself and come out and win next week."
Poulter looked to have the benefit of seeing playing partner Lee Westwood hole his birdie putt from an almost identical position on the 18th, but added: "It was probably a bad thing that I actually stood there and watched Westy's putt, because I think he pushed it slightly and it fell in the right edge.
"I knew my putt was going to break right to left. I hit it on what I thought was right edge on a decent pace and it broke across the hole."
Koepka follows in the footsteps of his good friend Peter Uihlein in winning on The European Tour and is now favourite to succeed Uihlein as the Sir Henry Cotton Rookie of the Year as well.
"It's awesome," added the 24 year old. "I played well. This field is first class, some of the best players in the world, and it's nice to get the win.
“I actually had a little vacation last week, which was nice, kind of recharged the batteries, didn't touch a club. I should take more vacations.
"To jump into the top 50 in the world (he started the week 61st) and be in all the Majors and I guess some of the World Golf Championships events, it will be special."
World Number Six Henrik Stenson, who will defend his title in Dubai next week, carded a flawless closing 64 to finish third on 14 under, one shot ahead of Miguel Angel Jiménez, overnight leader Wade Ormsby and English pair Andy Sullivan and Danny Willett.
Siem was another shot back alongside Westwood and revealed he had dislocated a rib while warming up in the gym before his round.
"My physio tried to crack it back in, it didn't work and then we went so see the chiropractor and they pushed it back in," Siem said. "I couldn't have a proper backswing but I played all right. I don't want to blame it on anything to be honest.
"I hit a lot of greens, had great birdie chances, just didn't hole a putt."
McIlroy, who was one of the first players to congratulate Koepka on Twitter, has already done enough with his four victories this season - including the Open and US PGA Championship - to be crowned European Number One for the second time.
