Four former world number ones will contest the women's ASB Tennis Classic in Auckland, with the full field now confirmed for the January event.
Organisers have confirmed former world number ones Caroline Wozniacki and Ana Ivanovic will join the Williams sisters Serena and Venus in the tournament.
Between them, they have won 30 Grand Slams, 160 WTA titles and spent 399 weeks or nearly eight years at world number one.
Caroline Wozniacki is among four former world number ones who will be competing at the ASB Classic. Photo: Photosport
Tournament director Karl Budge said, "This is unchartered territory for a sporting event in New Zealand. Any one of these four players could headline the tournament on their own."
The headline act and current world number two Serena Williams was confirmed for the tournament in September.
The 35-year-old American is the highest paid female athlete in the world, was named Sports Woman of the Year at the Laureus Sports Awards for the third time in 2016 and included in Time '100 Most Influential People'.
Wozniacki first came to Auckland in 2009 as a 19-year-old and became world number one a year later. She has won 25 WTA titles.
Ana Ivanovic Photo: Photosport
Ivanovic, who won the 2008 French Open, has competed at the Auckland tournament three times previously, winning the 2014 event when she beat Venus Williams in the final.
All up she has won 15 WTA singles titles and played in every Grand Slam for the last 12 years.
Ivanovic has had a frustrating 2016 with a recurring wrist injury and ended her season early in September in a bid to be fully fit for 2017, with Auckland to be her first tournament in several months.
She said the tournament is important for her confidence and to get match experience before the Australian Open in the second half of January.
This year's winner, American Sloane Stephens, has also confirmed she will be back to defend her title and the 23 year old has enjoyed wins over current world number one Angelique Kerber, both of the Williams sisters, along with Ivanovic and Wozniacki.
Serena Williams and ASB Classic trophy Photo: Photosport
The ASB Classic runs for two weeks with the women's tournament running 2 -7 January followed by the men's tournament 9 - 14 January.
Full Field for ASB Tennis Class, with world ranking in brackets.
1. Serena Williams (2)
2. Venus Williams (17)
3. Caroline Wozniacki (19)
4. Barbora Strycova (20)
5. Kiki Bertens (22)
6. Anastasia Pavlyuchenkova (27)
7. Sloane Stephens (35)
8. Jelena Ostapenko (44)
9. Naomi Osaka (47)
10. Ana Konjuh (48)
11. Johanna Larsson (50)
12. Yanina Wickmayer (51)
13. Annika Beck (52)
14. Julia Goerges (54)
15. Lauren Davis (61)
16. Lucie Safarova (62)
17. Ana Ivanovic (63)
18. Kirsten Flipkens (65)
19. Pauline Parmentier (71)
20. Danka Kovinic (72)
21. Madison Brengle (74)
22. Nicole Gibbs (75)
23. Kurumi Nara (78)
24. Mirjana Lucic--Baroni (81)