Kei Nishikori, who has been sidelined since August with a season-ending wrist injury, is determined to return with a level of fitness and form that will leave no question about his place among the game's best.

On Friday, the Japanese ace said his confidence is right where it was before a dislocated tendon in his right wrist forced him out of the Cincinnati Masters this summer and cut short his 10th season on the ATP tour.

Although the 27-year-old does not have a timeline for his comeback, coping with discomfort, frustration and lack of time on court is familiar territory, and he knows that when it comes to recovery from injury, haste makes waste.

"I can't say when I'll heal from my injury so I'm trying not to rush anything," said Nishikori, who spent almost a year off the court in 2009 after undergoing surgery on his right elbow.

"I'm aiming for the (Jan. 1-7) Brisbane International but it could be February, or even March, who knows. I want to make sure I'm in top form when I'm back on tour so I'm in a position to win a Masters or Grand Slam title. I also hope I'm mentally stronger and hungrier next season," he said.

Nishikori, who opted against surgery despite the recommendation of several doctors, said he is spending three to four hours a day in rehab and is limited to only an hour of daily court time at his Florida training base.

He does not have answers to all the questions about his health and fitness, but the tour veteran chooses to look on the bright side of a career that has been afflicted by injury.

"There was a lot of good that came from this experience. If it weren't for the injury I wouldn't have undergone a rehab period in Europe and I wouldn't have met the physical trainer who introduced me to a conditioning method that was new to me. I feel like it could change my body," he said.

With surprises like then-world No. 22 American Jack Sock winning the Paris Masters and Germany's 20-year-old Alexander Zverev riding a sensational season to the ATP Finals, Nishikori, who turns 28 next month, is aware he will be the target of a whole new generation of stars looking to make their mark in 2018.

"Seeing Zverev definitely made me feel old. It's rare to see a player that young play so well nowadays. I know I'm not considered a young player anymore. Of course, I feel pressure in that sense but that's the reality. Young players are always aggressive and unafraid. That's their weapon and I can learn from that," he said.

Nishikori, who was at his personal-high of No. 4 in the men's singles rankings as recently as this past March, dropped to 22nd at the start of November, his first time outside the top-20 since early 2014.

But he said time away from the game has only made him stronger, and he is eager to prove he is the same player he was before the injury -- only better.

"I know I'm getting tougher, so I'm actually looking forward to the challenge. With (Roger) Federer and (Rafael) Nadal back and younger players raising their game, the level of play has risen. I know I've been away from competition for about six months because of my injury, but I hope to make it back into the top five. I know I can," he said.