Kei Nishikori announces retirement from tennis at end of the season - 'I wish I could continue'

Japanese tennis star Kei Nishikori has announced that he will retire from professional tennis at the end of the current season. The former world No. 4 and 2014 US Open finalist made the announcement publicly, expressing regret with the words 'I wish I could continue.' Nishikori, who was the first Asian man to reach a Grand Slam singles final, has had his later career hampered by persistent elbow and wrist injuries.