Japan's Kei Nishikori can win a major on any surface next year, says his coach Michael Chang, a former world No. 2.

Chang won his only Grand Slam title at age 17 in 1989. Nishikori reached his first Grand Slam final at the 2014 U.S. Open, falling to Marin Cilic. The 24-year-old is currently ranked No. 5.

“The opportunity for him to win a major is going to be there for him at all four Slams,”  Chang told Tennis Channel. “There is no question about it. As far as going out there and saying we are going to win one, I don’t want to be in a situation where I am talking about Kei winning a Slam. I would rather continue taking things step by step and match by match rather than looking it as a whole. Sometimes when you look at it as a whole you get absorbed in that and only focus on that. I don’t want that to happen to us or to him. It is in the back of our minds but it has to happen point by point and that is the proper mentality.”

Chang added that if Nishikori is to win a major, he must stay healthy. Nishikori has dealt with injuries numerous times during his brief career; he withdrew from the Miami semifinals and retired from the Madrid final in 2014. But he did win consecutive five-setters en route to the U.S. Open final.

“Kei has made significant progress in this area, and probably the most evidence of that was the U.S. Open,” Chang said. “To play that many tough matches and recover and not have injury come from it was a really positive thing for Kei. From this point on it will hopefully get better and we won’t have to worry so much about injuries here and injuries there.

“If I have one goal for next year that would be for Kei to go out there and play 95 percent of the year healthy. To go through the year without having an injury or something happen that takes you out for two to three weeks at a time would be a huge accomplishment and that alone would take his tennis to the next level.”