Singapore: Defending champion Caroline Wozniacki of Denmark beat Petra Kvitova of the Czech Republic 7-5, 3-6, 6-2 in the WAT Finals last night.
It was Wozniacki's first win after losing to Karolina Pliskova in the Group White opener on Sunday.
Kvitova has suffered two defeats in as many matches after losing to Elina Svitolina.
Meanwhile, Japanese star Naomi Osaka has vowed to push through fatigue and atone for her error-strewn loss to Sloane Stephens in her WTA Finals debut on Monday.
An error-prone Osaka struggled with her rhythm and faded badly against Stephens, who won 7-5, 4-6, 6-1 in two hours and 25 minutes in the Red Group opener.
The 21-year-old came into the season finale as the in-form player, having won 14 of her previous 16 matches and capturing the US Open.
It has been a whirlwind for Osaka since her stunning victory over Serena Williams at Flushing Meadows in September.
"I haven't gone home [to Florida] since the US Open. So of course I'd love to go home, but I'm here right now and I want to do well," she told reporters.
"I want to give them [fans] a good match to watch. So for me that's my main priority, and I'm not really tired of that yet. So I just want to keep seeing how far I can go."
The world No.4 was visibly frustrated several times and dropped her racquet in disgust after failing to close out the second set in the ninth game.
Osaka, who had 46 unforced errors, said she hoped to keep her emotions in check moving forward.
In Monday's other Red Group match, Kiki Bertens of the Netherlands overcame top-seed Angelique Kerber in a thrilling 1-6, 6-3, 6-4 comeback victory.
Bertens incredibly flipped the script after being a set and a break down.
"I had a slow start but I'm really happy to have turned this match," she said. "I had a chat with my coach [Raemon Sluiter] and we decided for me to go for my shots and play more aggressive."
Bertens qualified just days before the tournament after world No.1 Simona Halep pulled out due to injury.
