Two-time Wimbledon champion Petra Kvitova on Wednesday became the fourth player to qualify for the WTA Finals, joining Simona Halep, Maria Sharapova and Garbine Muguruza in the eight-player field.
Czech star Kvitova won the season-ending showpiece on her 2011 debut.
“I am so excited to qualify for the WTA Finals in Singapore for the fifth straight year,” said Kvitova.
“I have been through some tough moments this season so I’m extra proud of myself for qualifying again and making it back to Singapore.”
Kvitova holds a perfect 3-0 record in WTA finals this year, winning titles in Madrid Open, Sydney and Connecticut.
The October 23-November 1 Singapore event will not feature world number one Serena Williams who decided to shut down her season earlier this month.