Singapore - Timea Babos and Kristina Mladenovic played a masterclass to upset world number one Barbora Krejcikova and Katerina Siniakova in the WTA Finals doubles decider on Sunday.
The world number three held the edge throughout to triumph 6-4, 7-5 in one hour and 24 minutes at the Singapore Indoor Stadium.
Babos defended her crown, having won last year's WTA Finals with Andrea Hlavackova.
Babos and Mladenovic qualified for the decider after a pulsating semi-final, defeating Ashleigh Barty and Coco Vendeweghe 10-8 in the super tiebreak set.
"The first tournament of the season, we won a slam (Australian Open) and the last tournament of the season we won... it's a privilege," Mladenovic said after the match.
The Hungarian-French pairing closed in on championship glory by breaking in the fifth game of the second set but Babos was unable to consolidate.
Babos upped her game in the 11th game to break Siniakova's serve and then Mladenovic held her nerve to close it out.
Even though they fell short in the final, the Czechs had already secured the world number one ranking.