World number one Dustin Johnson imploded and Justin Rose stormed back from eight shots behind overnight to win the $9.75 million WGC-HSBC Champions by two strokes in a thrilling finale in Shanghai on Sunday.
The Englishman Rose, who started the concluding day joint fourth, fired a 67 to finish 14-under-par 274 and somehow emerge victorious from a nail-biting four-way fight that also included Henrik Stenson and Brooks Koepka.
A demoralised Johnson finished tied second with Stenson and Koepka after a horror five-over-par 77.
Under normal conditions, the odds would have been on Johnson. But Rose said swirling wind blowing through Sheshan Golf Club meant the conditions were ripe to pull off the biggest comeback of his career.
"It's the kind of day you hope for, dream for, but a lot of things need to go your way in order for a day like today to happen, coming from eight shots behind, especially going against a player like DJ (Johnson)," said Rose, 37.
"It's been a long time since I've won, or at least it feels like that," added Rose, whose stunning five under in the back nine propelled him to victory.
Rose has won a title every year since 2010 if the Olympics last year in Rio are included.
"This is my only win in 2017. Left it late this year, but it feels amazing."
Johnson was chasing a sixth prestigious World Golf Championship (WGC) crown and looked to have put himself out of sight on Saturday evening with a handsome six-shot lead on fellow American Koepka, who was second overnight.
But on another blustery day, this time accompanied by smog and cooler temperatures, Johnson started with two bogeys to immediately give the chasing pack hope on the par-72 course.
Johnson, who triumphed in Shanghai in 2013, failed to get his putter going all day and was meticulously pegged back by a combination of Rose, Stenson and Koepka.
The 33-year-old said: "I didn't make any putts. I felt like I rolled it good, just nothing was going in the hole.
"I felt fine all day, I just could never get anything going and didn't hole any putts. It was pretty simple."
- 'Best till last' -
There was a moment of levity when a black swan invaded the course.
But there was nothing to smile about for Johnson when he carded another bogey at the par-three 12th.
Johnson's good friend Koepka and last year's runner-up Stenson were now a scarcely believable two shots behind and Rose was creeping up fast.
Rose, playing in the group ahead, sank birdies at 11, 13 and 14 to join Koepka and Stenson in hunting down Johnson.
Reigning US Open champion Koepka whittled Johnson's once-healthy lead down to a wafer-thin one shot with a birdie at the par-five 14th.
Another birdie chance went begging for Johnson at the 15th and Rose made a seventh birdie at the 16th to draw level in the lead.
Johnson's disaster of a day unravelled further when he found the bunker with his tee shot at the par-four 16th.
His pursuers sensed blood when he carded bogey and Rose and Stenson catapulted over him into the joint lead with two holes to play.
Rose made another birdie at the 17th and signed off with par at the 18th, while Stenson's ill-timed bogey at the 17th did for the Swede.
"It's unbelievable. Obviously we all know the position DJ was in and I think today was the kind of day that the leader probably didn't want," said Rose.
"It was really tricky out there and obviously I played one of the best back nines I've played in forever.
"To shoot 31 on the back to come through -- saved my best till last."