Dominika Cibulkova has delivered a serving masterclass to secure the biggest victory of her career, the Slovakian storming to a 6-3 6-4 triumph over world No.1 Angelique Kerber to claim the WTA Finals title.
Cibulkova, making her debut in the elite eight-woman event, was at her effervescent best against her overwhelmed opponent, refusing to yield as she sealed an unlikely victory with a monumental hold of serve in a tense finale.
Kerber, the Australian and US Open champion, is known for her resilience and fought to the bitter end of Sunday's absorbing contest but Cibulkova gritted her teeth and claimed victory with a lucky net cord on her fourth championship point.
"Coming here for the first time and winning the biggest tournament of my life, I just have no words," said Cibulkova, who lost her first two matches in Singapore this week.
"When the ball just went in on the match point, it was the happiest moment of my life."
Cibulkova lost a tight three-setter to Kerber in her first round-robin match but turned the tables on the German in the final and will now climb to a career-high world No.5.
The 27-year-old enjoyed a nerve-settling comfortable hold to open the contest and began attacking a tentative Kerber, her booming forehand securing an early break as she raced ahead 3-0.
Kerber was growing into the contest but struggling to contain her opponent's all-action style and the German would have been relieved to stave off another threat in her next service game.
A loose forehand was the first sign of a drop in intensity in Cibulkova's game and Kerber utilised her exceptional defence to force the Slovakian into a few more errors as she broke back to for 3-2.
Cibulkova would not be denied, however, and her low-trajectory drives into the corners were becoming a problem Kerber battled to solve.
The seventh seed swarmed all over the German to break again and pull 5-2 clear.
Kerber secured her easiest hold of the match to force Cibulkova to serve for the set and the Slovakian proved up to the task, emphatically claiming the opener with a forehand winner on her first set point.
The German appeared more focused at the start of the second set but Cibulkova was timing the ball beautifully and matching her opponent shot-for-shot, threatening a break in the third game which Kerber survived.
Unable to find a first serve, Kerber was struggling to stay in the contest as Cibulkova continued to feast on her apprehensive play and the Slovakian stormed ahead with a brilliantly worked break in the seventh game.
Cibulkova held easily to move to the brink of the title but Kerber held firm to put the onus on her to serve it out.
"I gave everything I had on the court and it's an honour to play on the big stage in front of my incredible fans," Kerber said.
"I've had an incredible year and I'm looking forward to the next one."