Lee Soomin claimed his maiden European Tour title after outlasting the chasing pack by two shots at the Shenzhen International.
A fifth day was required as thunderstorms wreaked havoc, forcing the fourth round to be pushed back to Monday, with South Korean Lee, Lee Slattery and Alexander Levy in a three-way tie for the lead.
Joost Luiten, Brandon Stone and Scott Hend were also in contention during the closing stages of the rain-affected tournament at Genzon Golf Club.
But the 22-year-old Lee, who had five holes remaining when he resumed, birdied the 16th hole and eagled the next for a final-round 71 and a wire-to-wire victory at 16 under, despite bogeying the 18th.
Dutchman Joost (68) and South Africa's Stone (68) were two shots adrift as the European Tour had a Monday finish for the first time since 2011.
After posting 71's, Slattery and Levy dropped down to a tie for fourth at 13 under, alongside Hend, who was bogey-free in his six-under-par 66.
Bradley Dredge (72) was a shot further back in sole possession of seventh.
Two-time major champion Bubba Watson, meanwhile, rose to eighth, six shots behind Lee following his 66.
As for defending champion Kiradech Aphibarnrat (76), he ended the tournament four over the card.