By John O'Brien
Slovakia's Dominika Cibulkova completed a remarkable debut at the WTA Finals after storming to victory in an upset 6-3 6-4 triumph over top seed and world No.1 Angelique Kerber.
Cibulkova lost her first two round robin matches before beating Simona Halep to squeeze into the semi-finals at the Singapore Indoor Stadium.
Career highlight: Dominika Cibulkova celebrates victory in WTA singles final.Credit: Clive Brunskill
Hher victory in the title showdown on Sunday matches the feat of last year's winner Agnieszka Radwanska, who captured the 2015 title with a 1-2 record after the pool stage of the tournament.
The world number eight's first defeat at this year's tournament was a tight three-set loss to Kerber, winner of the Australian and U.S. Opens in 2016, but she turned the tables on the German in the final to register the biggest victory of her career.
Singapore sling: German world No.1 Angelique Kerber was defeated in the WTA final.Credit: Clive Brunskill
In the earlier doubles decider, Russian pairing Elena Vesnina and Ekaterina Makarova claimed their first WTA Finals title with a 7-6(5) 6-3 victory over Bethanie Mattek-Sands and Lucie Safarova.
The 2016 Rio Olympic champions were broken when they served for the opening set at 5-4 but regrouped in the tiebreak to edge ahead of the third seeded American-Czech partnership before a single break in the second set proved enough to seal the title.
Left-hander Makarova finished off the contest on the pair's fourth championship point when Mattek-Sands could only get the frame of her racket to a booming serve out wide.
"It was such a great match and a real pleasure to play in," Vesnina said. "It was really tough until the end, a really close match and we were so happy that we won it."
On the double: Champions Ekaterina Makarova (2nd right) and Elena Vesnina (right) of Russia pose with Bethanie Mattek-Sands (2nd left) of the United States and Lucie Safarova (left) of Czech Republic after the WTA doubles final.Credit: Matthew Stockman