World number one Simona Halep has been drawn in the same group as Elina Svitolina, Caroline Wozniacki and Caroline Garcia for the WTA Finals in Singapore.
Top seed Halep is in the Red Group for a prestigious season-ending tournament she was runner-up in three years ago.
Halep, who this month went to the top of the rankings for the first time in her career, has won only one title this year and missed out on a maiden grand slam title when Jelena Ostapenko beat her in the French Open final.
Six of Halep's rivals head into the tournament, which starts on Sunday, with the opportunity to replace her as world number one.
Garbine Muguruza, on top of the rankings briefly before Halep dislodged her, is the favourite to win the title and the Wimbledon champion will be up against Karolina Pliskova, Venus Williams and Ostapenko in the White Group.
The White Group will be a battle of the heavy-hitters, with Williams the only previous winner of the event to have qualified this year.
Muguruza and Ostapenko are the only two of the 2017 grand slam winners among the eight competitors.