Jon Rahm carded a closing 67 to win the DP World Tour Championship, Dubai as a late slip from Justin Rose handed Tommy Fleetwood the Race to Dubai title.
Rose had looked on course to claim both the eighth Rolex Series event of the season and the Race to Dubai as he turned in 32 at Jumeirah Golf Estates but three bogeys on a dramatic back nine brought him back to the pack and opened the door for Rahm.
The Spaniard came home in 33 to get to 19 under and win his second Rolex Series title by one shot, with Rose slipping back into a tie for fourth that was not good enough to overturn Fleetwood's 256,737-point advantage in the Race to Dubai Rankings presented by Rolex.
Fleetwood signed for a closing 74 to finish in a tie for 21st and end a season that has brought wins at the Abu Dhabi HSBC Championship and the HNA Open de France as Europe's Number One.
Shane Lowry and Kiradech Aphibarnrat finished a shot behind Rahm at 18 under, one clear of Rose, Dean Burmester, Dylan Frittelli and Sergio Garcia.
Rahm - who was handed the Sir Henry Cotton Rookie of the Year award this week - adds this win to his Dubai Duty Free Irish Open Hosted by the Rory Foundation title and becomes the first player to win multiple Rolex Series events.
"It's hard to sum it up," said Rahm. "An incredible week, I could not be more proud of what I've done this week. It could be very easy to just be content with getting the award and just being here and trying to play the best.
"Having the weekend that I've had, actually shooting 12 under on the last 36 holes, bogey-free round today, it's really special.
"I didn't plan on being here at the beginning of the year and I sure didn't plan on winning it so it's an incredible feeling."
The margins were so tight in the season-long battle that had Rose finished one shot better he would have won the Race to Dubai, while a birdie rather than a bogey on the last and a play-off win over Rahm would have seen Garcia take the crown.
In the end, Garcia slipped to fourth in the Rankings as he was overtaken by countryman Rahm, with Rose finishing second behind fellow Englishman Fleetwood.
I could not be more proud of what I've done this week - Jon Rahm
It looked like a procession for Rose on the front nine as he took advantage of the par five second, holed a four-footer on the third, a 15-footer on the fifth and then a brilliant 25-foot putt down the hill on the seventh to turn in 32 with a one-shot lead.
Rahm had started the day a shot behind the 2013 US Open champion and while he made birdies on the third and seventh, he was three back at the turn with a birdie on the tenth edging him closer to the leader.
A poor bunker shot on the 12th led to a Rose bogey and left the door ajar, with Rahm getting up and down from a bunker at the side of the 14th for a birdie and a share of the lead.
Fleetwood had made three birdies and three bogeys to sit at level par and still looked likely to miss out on the season-long honours before more drama unfolded on the 14th.
Rose put his second in the water and while he recovered well to leave eight feet for par, he missed the putt and fell out of the lead both in the tournament and the Race to Dubai.
Rahm went right off the tee on the 16th but put his recovery to eight feet for a fifth birdie of the day and the solo lead.
Fleetwood finished bogey-bogey but with Rose needing to finish alone in fourth to catch him at that point, the 26 year old remained in the ascendancy.
Rose found a fairway bunker off the 16th tee and when he came up short of the green and failed to get up and down, he was left needing an eagle on the last to get into a tie for second.
He made a birdie to sign for 70 but it was ultimately disappointment for the man who was seeking his third win in a row.
Ireland's Lowry made ten birdies and a single bogey in a stunning 63, with a closing birdie handing Thai Aphibarnrat a 67 and a tie for second.
Garcia signed for a 65 with South African Burmester registering a 68 and countryman Frittelli a 69.
England's Tyrrell Hatton and American Julian Suri finished at 16 under, with two more Americans in Patrick Reed and Peter Uihlein a further shot back.