Wearing her Australia cap, Ashleigh Barty is looking hungry to capture gold for her home country.
Grand Slam champions Andy Murray and Novak Djokovic grabbed a solid final practice in Tokyo before the games commence on Friday.
The world No. 1 will face Bolivia's Hugo Dellien in the first round.
Naomi Osaka was back on the court for her final practice session before kicking off her Olympic campaign against China's Zheng Saisai.
Nishikori will take the doubles court on Friday with partner Ben McLachlan. The two will face Portugal's Joao and Pedro Sousa.