Justin Rose capitalised on world number one Dustin Johnson's final-round capitulation to win the WGC-HSBC Champions by two shots.
Johnson looked destined to become the first player to win three World Golf Championships titles in the same year at Sheshan International Golf Club, where he started the day with a six-shot lead.
The American let his commanding advantage slip on Sunday, though, carding a five-over 77 to finish tied for second with Brooks Koepka and Henrik Stenson on 12 under.
Rose took advantage of Johnson's woes, raising his game on the back nine to overcome an eight-shot deficit and claim his first title of the year courtesy of a five-under 67 to finish 14 under.
The Englishman was six shots off the lead at the turn, but came up with five birdies in his last eight holes to claim an unlikely victory in Shanghai – his first since being crowned Olympic champion last August.
Rose and Stenson shared the lead with two holes to play after Johnson's fifth and final bogey of a miserable day at the 16th and the Swede bogeyed as the 2013 U.S. Open champion came up with an eighth gain to take a two-stroke advantage.
Both Rose and Stenson, who were involved in an epic duel at the Olympic Games in Rio last year, made par at the last and pars for Johnson at the final two holes were not enough to undo the damage.
Johnson failed to make a solitary birdie after bogeying his first two holes and also dropped three shots on the back nine, while Stenson signed for a two-under 70.
U.S. Open champion Koepka, the leader after the first round, ended his week with a one-under 71, paying the price for a double-bogey at the 15th.