US Open winner Naomi Osaka faces resurgent Wimbledon champion Angelique Kerber and there's also a duel between holder Caroline Wozniacki and ex-champ Petra Kvitova in group play at the WTA Finals in Singapore.
Wozniacki is the top seed at the prestigious eight-player season finale, starting on Sunday, because world No.1 Simona Halep has withdrawn with a back injury.
"It's always difficult to withdraw from a big tournament," Halep said.
"Actually, I think it's the first time in my life. So it was a tough decision but it's better for my health."
Halep's absence lifted Kiki Bertens into the field, the first Dutch woman to be ranked inside the top 10 since Brenda Schultz-McCarthy in 1996.
"I'm very happy with my season and to finish it off at the WTA Finals is the ultimate prize," said Bertens.
"I have great memories in Singapore from reaching the doubles final last year."
The 26-year-old Bertens faces three grand slam champions in the Red Group in Osaka, Kerber and Sloane Stephens, the latter a US champion from 2017, at the October 21-28 event.
Kerber won Wimbledon in July, shaking off a terrible 2017 season with her third title at the majors. She surprisingly split with coach Wim Fissette early in the week and will be trained by hitting partner Andre Wiesler in Singapore.
"I think I am ready," the 2016 runner-up Kerber said.
"The season is long but I don't lack motivation for the WTA Finals."
Osaka hopes to shine again in Singapore after her heroics at the US Open, being a tournament novice just as her group rivals Bertens and Stephens.
Wozniacki meanwhile was a finalist in 2010 before winning the title in 2017, with her first grand slam win following shortly after in January at the Australian Open.
She faces Kvitova, champion in 2011 and runner-up in 2015, in the White Group which also includes fifth-ranked Czech Karolina Pliskova and Ukrainian number six Elina Svitolina.
Svitolina won three trophies in Brisbane, Dubai and Rome while Pliskova claimed the Stuttgart and Tokyo crowns.
"I'm delighted to be appearing at the WTA Finals for the third time," Pliskova said.
"I have such great memories from playing in Singapore in 2016 and 2017, and I can't wait to close out the year competing against the other elite players of 2018."
