Former World number one Caroline Wozniacki will again be a headline act at January's ASB women's tennis classic in Auckland.

The Dane has been confirmed for her fifth appearance at the Classic on the back of qualifying for the season ending WTA tour finals in Singapore.

Wozniacki is 6th in the rankings having played in six tour finals this year, recently crushing world number one Garbine Muguruza in the final in Tokyo.

Wozniacki says Auckland is one of her favourite stops on tour.

"I can't wait to be back in Auckland next year, currently I'm in Asia just trying to finish out the year strong.

"I am so pumped to be coming to Auckland, I love Auckland, such a great city.

"The fans are amazing, I just love playing in that stadium and going back and eating at the great restaurants. There's so much to love in Auckland."

Wozniacki joins world number 11 Agnieska Radwanska in what is shaping as a strong women's field in Auckland, but US Open champion Sloane Stephens looks unlikely to join them.

She had wanted to return to Auckland but organisers are unable to guarantee Stephens a place due to Tour rules only allowing one top ten ranked player in the field.

17th ranked Stephens wants to play Auckland but tournament director Karl Budge can't give her a guarantee because she's likely to finish in the top 10 by the end of the season.

"There's a second Tour finals in China that offers pretty big rankings points.

"There's a strong chance she could certainly finish there or there abouts so it makes our life, at this time, a little bit more challenging.

"It's not completley dead, but her ranking could really hurt us. We've got to see where Sloane finishes and if we're able to have this formal conversation with her again."

The American won the title in Auckland in 2016 but was unable to defend this year due to injury.