Spain's Gonzalo Fernandez-Castano won the BMW Masters by a single stroke over Italy's Francesco Molinari and Thailand's Thongchai Jaidee after finishing 11-under par on Sunday.

Meanwhile, Rory McIlroy had another roller-coaster day.

Fernandez-Castano, lying second overnight at 7-under and playing in the final group, looked to have sealed his victory in spectacular style by chipping in for birdie at the 17th hole to open up a three-shot lead at 13-under par.

However a few nerves kicked in on the tough 471-yard 18th as the Spaniard said he "tried to play conservatively" and found fairway and greenside bunkers on his way to a double-bogey six - the only blemish on a card of 4-under 68 that included six birdies.

"I was glad I had a three-shot cushion," he said after pocketing the winner's cheque of $1.16 million that propelled him up to fourth in the Race to Dubai European Tour standings.

Fernandez-Castano seems to have a liking for Asia and Shanghai in particular, having won across the city at Tomson Golf Club at the BMW Asian Open in 2006 and the Singapore Open in 2011.

"I can't believe it was seven years ago," Fernandez-Castano said. "I always love playing in China. Great country and it's been a great week."

This was his first win since the 2012 BMW Italian Open.

McIlroy had stomped away in frustration after his third round on Saturday ended with a double bogey. On Sunday he birdied the monster par-4 18th to finish with a 73.

Before he dashed to the airport to fly to the southern island of Hainan for a "lot of fun" at a money-making exhibition match with Tiger Woods at Mission Hills on Monday, he said could still take positives from the European Tour event.

"Definitely it wasn't the week I was hoping for," said the 24-year-old former world No 1. "I feel like my game's better than what the scores suggest."

McIlroy drove the ball supremely all week, looking to be back near his best with his long game. But around the greens it was a different story.

"I thought the putter got a little better as the week progressed. I definitely left a few out there on the greens, for sure," said the Northern Irishman.

"I'm giving myself plenty of chances for birdies ... sooner or later they are going to fall and I'll start shooting some lower scores."

The 23-year-old leader for three rounds, Luke Guthrie of the United States, trod water on a calmer day that saw some very low scoring, finishing fourth at nine-under par after a 71.

Molinari carded a spectacular eight-under 64, courtesy of five birdies and an eagle on the back nine, to grab a share of second place.

"I had dinner with Gonzo (Fernandez-Castano) last night. I think he was expecting someone to charge today, but probably not me," Molinari joked afterwards.

Thongchai provided the perfect response after being surprisingly overlooked for the Presidents Cup last month. He flew the flag for Asian golf with a closing 66 to finish 10-under par.

Defending BMW Masters champion Peter Hanson of Sweden, playing his first event since the US PGA championship in August because of a back injury, set the early clubhouse lead with an amazing birdie blitz.

The Swede carded 11 birdies and two bogeys in a 9-under round of 63, the lowest of the week, to take him to a share of eighth place - a huge turnaround after his opening-round 79 on Thursday.

Fellow Swede, Race to Dubai leader and FedEx Cup champion Henrik Stenson, appeared to have finally overcome a wrist injury that troubled him earlier in the week.

He shot a seven-under par final round of 65 to share 34th place on two-over par for event.