The WTA Tour season comes to a conclusion in Singapore this week with the WTA Finals. The event has already been hit by the loss of world No 1 Simona Halep with a back injury, which has led to Kiki Bertens completing the line-up.
Here is a look at the eight players who will compete and what to expect when the action gets underway on Sunday.
White Group
Caroline Wozniacki
Wozniacki, 28, won the title in Singapore 12 months ago and that proved the catalyst for her breakthrough moment in January when she finally claimed her first grand slam crown by defeating Halep in the Australian Open final.
She has been rather underwhelming since then. Until her success in Beijing earlier this month, her lone other tournament win since Melbourne was in Eastbourne.
Beijing was won without beating anyone ranked higher then 20th so the Dane's form is questionable going to Singapore and it would be a surprise if she became the first player since Serena Williams to win back-to-back titles.
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Petra Kvitova
Until June it had been a strong year for the two-time Wimbledon champion.
The 28-year-old Czech had fully recovered from the injuries suffered in a knife attack in the winter of 2016 and won five WTA titles, but since her success in Birmingham she has dipped.
A run to the semi-finals at Cincinnati in August is as good as it has been since then and the world No 7 will need to raise her game considerably in Singapore to be a contender.
Elina Svitolina
Three titles for Svitolina in 2018, including successfully defending her Dubai Duty Free Tennis Championships crown in February.
When the 24-year-old Ukrainian defeated Halep in the Madrid final in May on clay she looked well set to win her first major at the French Open. Instead she crashed out to Mihaela Buzarnescu in the third round and her form has been middling since then.
If the world No 6 can find the level of play with which she dominated in Dubai, reaching the semi-finals should be the very least she can achieve.
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Karolina Pliskova
A solid year for Pliskova which has kept the world No 5 near the top of the women's game.
Three titles in total and she comes into the event on the back of a run to the final in Tianjin and a victory in Tokyo against Naomi Osaka.
Usually gets better the longer she is in a tournament so if the 26-year-old Czech can make the knockout stages she will be a force to be reckoned with.
Red Group
Angelique Kerber
The former world No 1 has a welcome return to the top of the game after an indifferent 2017.
Winning Wimbledon was the highlight for the 30-year-old German, but she has gone off the boil subsequently.
World No 3 Kerber has not gone further than the last 16 at any event since then so a strong run in Singapore will be a surprise.
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Naomi Osaka
The form player going into the tournament. Osaka, 21, held her nerve in difficult circumstances to deservedly win the US Open in September for a first major.
The Japanese No 1 also prevailed at Indian Wells in April, and her level has remained high since her success in New York with a runners-up spot in Tokyo and then a run to the semi-finals in Beijing.
The only doubt on the world No 4 may be tiredness following a hectic schedule, but she is undoubtedly the player to beat.
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Sloane Stephens
An encouraging year for the 25-year-old American that has proven her 2017 US Open title was no fluke.
Won in Miami and a runners-up spot at the French Open proved that when she is on song she can be difficult to face.
World No 8 Stephens' form has dropped off since her surprise exit to Anastasija Sevastova in the quarter-finals of this year's US Open, but she will be disappointed if she does not at least reach the semi-finals.
Kiki Bertens
The world No 10 is the late call-up to replace the injured Halep and she faces a tall order to make it out of the group, given the opponents she will face.
Her season highlight came in June when she beat Halep to win in Cincinnati, and a runners-up position in Madrid also showed what the 26-year-old Dutchwoman is capable of when she is at the top of her game.
Predictions
The White Group is hard to call, but Wozniacki and Pliskova to make it through as the top two.
In the Red Group it will be Osaka and Stephens who reach the semi-finals.
Osaka has played the best tennis in recent months and she will cap a memorable 2018 by lifting the title, beating Stephens in the final.