Kei Nishikori has endured a difficult past few years on the ATP Tour, having struggled with injuries.
The Japanese star, who reached the peak of his career in 2014 when he made the US Open final, has made just three Grand Slam appearances in the last four seasons.
Nishikori featured solely at the Australian Open this year, where he managed to earn one win before being knocked out in the second round.
Now ranked 156th in the world, Nishikori will have to qualify for a Grand Slam for the first time since 2010 in Melbourne next season.

Kei Nishikori speaks about the upcoming Australian Open
Talking about having to qualify for the Australian Open in an interview with WOWOW, Nishikori said: “It feels a bit strange.
“First of all, I want to play as many matches as possible. The most important thing is to win as many matches as possible and gain confidence.
“I’ve had good results in Melbourne in the past, and it’s a tournament I like, so I want to play good tennis.”
Nishikori’s best result at the Australian Open is a quarterfinal finish, which he has achieved four times.
He then said: “I want to heal my injury and play as many matches as possible. I’m not able to play as many matches as I used to.
“I’d like to monitor my physical condition and consult with my doctor, and get back to my normal tennis form in the tournaments I can play and achieve good results.”

Kei Nishikori discusses Jannik Sinner and Carlos Alcaraz
The overwhelming favourites at this year’s Australian Open will be the top-two ranked players in the world; Carlos Alcaraz and Jannik Sinner.
Discussing the ‘new two’, Nishikori said of their games: “It’s simply fun to watch. They give you the feeling that you’re watching a Federer match, wondering what kind of shots they’ll make.
“There are other strong players like Fritz and Draper, but I think those two are the ones who get you excited. Their timing is fast, and the trajectory and accuracy of their shots are amazing.
“I think Sinner is particularly fast at developing his game. That being said, I don’t think there’s any other player in the world who can imitate him.”
Alcaraz is bidding to complete the Career Grand Slam Down Under, while Sinner is looking to three-peat.
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