Caroline Wozniacki's 2018 campaign has been a mix of peaks and valleys

A WTA rankings update:

The 12 months between the 2017 and ’18 editions of the Pan Pacific Open in Tokyo have been a roller-coaster ride for world No. 2 Caroline Wozniacki, one that appears to be on a perpetual downward slide of late.

Last year’s title-winning run at the Premier event kicked off a torrid stretch for the Dane. Weeks after winning the tournament for the third time, she captured the WTA Finals for the biggest title of her career. It didn't take her long to surpass that achievement as she won her first Grand Slam title at the Australian Open, a feat that brought her back to the top of the rankings six years after she last held that spot.

After overcoming injuries and a struggle with her form for years—along with the stigma of being one of the best players to have never won a major—it was assumed that Wozniacki would then go deep at the other majors or at least challenge for some of the tour’s more prestigious titles.

That’s been far from the case.

Returning to Tokyo last week, Wozniacki’s stay at the tournament was a brief one: The 28-year-old dropped her opening match to Camilia Giorgi to continue a string of poor results on hard courts, undoubtedly her best surface. The two-time US Open finalist, whose preparation for the Grand Slam was suboptimal due to leg injuries, fell in the second round in New York in her most recent on-court appearance.

Mixed results on the clay and grass preceded the hard-court swing. She did manage to reach the round of 16 at the French Open and Wimbledon, and won her second title of the year on grass at Eastbourne.

For any number of players, two titles—one of them a Grand Slam—would be a career year. More was expected of Wozniacki, though, considering how far she had to come the past few years to re-establish herself among the game’s elite.

Right now, it appears as if the fight has taken a lot out of her. A letdown would be hard for any player to fend off after having finally achieved her career goals. Now, to add to her legacy, she’ll have to dig deep once again. Every week on the WTA Tour offers an opportunity to hit the reset button and Wozniacki will be doing so in Wuhan. She's beaten qualifier Rebecca Peterson in her first match and her chances to go deep in the draw have improved significantly with Elise Mertens and Karolina Pliskova both losing.

Wozniacki is widely regarded as one of the best counterpunchers in the game, and has made her mark by outmaneuvering and outthinking her opponents. Will she be able to maintain that pace as she enters the latter stages of her career? Throughout the bulk of 2018, that hasn’t been readily evident, but a strong performance in the last few weeks of the year might be enough to reignite the spark that’s brought her back to the top of the game.