Scotland's Robert Thornton defeated world number one Michael van Gerwen 5-4 to win the World Grand Prix in Dublin.
Thornton's only other major success in the PDC came at the 2012 UK Open.
The first four sets were shared before 48-year-old Thornton went 3-2 up as Van Gerwen, 26, missed eight darts at a double to wrap up the fifth set.
The Dutchman trailed 4-3 after missing two more darts to take the seventh set and Thornton took advantage, sealing victory a shot at with double top.
"It's one of my traits, I've got the heart of a lion. I never give in, I'll keep fighting until the end," Thornton told Sky Sports.
"To win a title, you need to beat the man [Michael van Gerwen]. If you want to win a tournament, this is the way to do it."