The Dane admitted it was a shock when she received the diagnosis. She had been noticing extra fatigue and joint soreness after Wimbledon, which continued throughout the second half of her season. After various tests, the former World No 1 received confirmation just before Flushing Meadows.
There is not yet a cure for the condition, though sometimes patients can go into remission. It's estimated that women are affected more than twice as much as men, and more than 25 million people worldwide have the condition.
With the physical demands of tennis — the constant training, the gruelling matches and the longest season in professional sports — Wozniacki knows she has a tougher battle than most.
"I'm managing it," said Wozniacki. "Obviously every day is a new day and you kinda just feel how you feel but I feel pretty good about it. It's about figuring out what little things work for me, and what makes me feel good and you just kinda learn along the way."
She also has to deal with the constant travel, as the WTA tour criss crosses the globe.
"You learn a few things," said Wozniacki. "You learn to stretch, you learn to stand up a bit sometimes so it definitely helps."
Wozniacki's arrival into Auckland was delayed by 24 hours, after storms in the USA affected her a domestic connecting flight from Miami to Houston on Saturday.
She waited at the airport for a few hours, then returned home, before making the journey from Florida to New Zealand, via San Francisco, the next day.
"It's not bad," said Wozniacki. "I can't really help the storms or the weather".
Wozniacki, who lost the 2018 Classic final to Julia Goerges, the second time she has been runner up in Auckland, is unconcerned about a potentially tough run back to the decider, with both Venus Williams and Victoria Azarenka in her quarter of the draw. She faces a wildcard in the first round.
"I never look at the draw...so let's just see what happens."
Whatever unfolds, Wozniacki is sure to be well received on the Stanley Street courts.
Not only is she a fan favourite, who usually performs well here, but there is also likely to be special admiration for her proactive and brave stance since her diagnosis.