Kei Nishikori's coach Michael Chang believes that it is only a matter of time before the world number six wins his maiden grand slam.
Nishikori came close to becoming the first Asian man to win a grand slam title at the US Open in 2014 when he lost to Marin Cilic in the final.
The 25-year-old followed up that performance with quarter-final appearances at the Australian Open and the French Open, and Chang is confident that Nishikori is well on his way to breaking new ground by becoming the first Asian man to win a grand slam.
"Obviously Kei's really the best prospect right now," Chang told The Straits Times. "He's beaten all the best players in the world. He's going to have opportunities (in 2016) for sure."
However, in order for Nishikori to win a grand slam, Chang, who became the youngest male player to win a grand slam when he triumphed at Roland Garros at the age of 17 in 1989, believes that the Japanese ace has to enhance the physical and mental aspects of his game.
"We just have to peak him well, prepare him physically and mentally as well," he said. "I don't think he's far away."