TOKYO - Japan's former world No. 4 Kei Nishikori lost in the first round of the final tournament of his career at the Japan Open on Thursday, going down to Frances Tiafoe of the United States 6-4, 6-4.
The 36-year-old Nishikori, the first Asian male player to reach a Grand Slam singles final at the 2014 U.S. Open, announced in late April that he would retire at the end of this season.
