Tennis: John Isner and Caroline Wozniacki headline ASB Classic

John Isner and Caroline Wozniacki. Photo / Getty Images

ASB Classic organisers have once again signed big serving American John Isner to headline the men's field for the 2016 tournament, despite his no-show in Auckland this year.

Isner was unveiled as one of two star signings for the January tournament at a launch event tonight, with former world number one and last year's runner-up in the women's draw, Caroline Wozniacki, also set to return to Auckland.

Isner, a two-time winner of the men's event, left organisers high and dry this year when he withdrew just a week out from the tournament. It was just one of a string of withdrawals to hit the event after a Frenchman Gael Monfils pulled out due to personal reasons, while a back injury forced long-time attendee David Ferrer out just days before the opening round.

But it was Isner's decision to skip the tournament citing tiredness that was particularly galling for organisers. Isner opted to venture straight to Melbourne to prepare for the Australian Open after what he described as a "big week" at the Hopman Cup the week prior.

However tournament director Karl Budge is confident the world number 11 will follow through on his plans this year.

"We know what happened with him [this] year, but he was pretty upfront with us all year and said 'I want to come back, I want to come and play and win my third title here'," said Budge.

"He's not playing the week before us, which was the big concern. This year he played the week before and thought it was too much loading to play two weeks of tennis at the start of the season right before a grand slam. But this time he will be kicking off his year fit and healthy in Auckland."

Isner said he is excited to be returning to Auckland, where he won his first ATP title in 2010.

"I have so many great memories and I'm sad I missed the tournament this year but next year I'm going to make it up to all those that come to watch," he said.

The 30-year-old American finished off the 2015 season in fine form, edging world no. 2 Roger Federer en route to a quarter-final appearance at the final Masters event of the season in Paris last week. It's been another productive year for the American where he reached two finals, two semifinals and six quarter-finals to finish the year ranked just outside the top 10.

Wozniacki comes to Auckland after sliding to 17th in the world rankings - in what proved to be a win for Budge.

As a international category tournament, only one top 10 player can feature in the draw, but with defending champion Venus Williams having already signed up, the only way to secure Wozniacki for a second straight year was if she had a quiet finish to the year.

"Things got a bit nervous there for a while, but Venus ended up getting in the top 10, and that tipped Caroline out," said Budge.

"It worked out really well - you feel a bit guilty saying that but for selfish reasons it's nice that we can get two superstars that are quite clearly top 10 calibre. When rankings are kind to us you've got to take those opportunities because there's plenty of times when they're not."

Isner and Wozniacki join Williams and Jo-Wilfried Tsonga as they key drawcards for the event, which from next year will be run as one tournament under the banner of ASB.