Ash Barty and home favourite Naomi Osaka start their respective quests for Olympic gold against Sara Sorribes Tormo and Zheng Saisai, while Novak Djokovic opens against Hugo Dellien.
In a stacked women's draw, world number one and Wimbledon champion Barty has a tough opening assignment and could face French Open finalist Anastasia Pavlyuchenkova, the 13th seed, as early as round three.
Spectators may not be in attendance at Tokyo venues for the Olympics but Japanese fans will be rooting for Osaka, who returns to action after a two-month hiatus with the four-time grand slam winner having spoken openly about mental health and anxiety issues.
Viktorija Golubic or Maria Camila Osorio Serrano would await Osaka if she can get through round one, but a dream final with Barty is no shoo-in given 15 of the world's top 20 on the WTA Tour are in action including each of the nine leading the race for the 2021 WTA Finals.
Aryna Sabalenka (3), Elina Svitolina (4), Wimbledon runner-up Karolina Pliskova (5), Iga Swiatek (6) and Garbine Muguruza are all featuring in Tokyo.
The men's side has been hit by a spate of withdrawals, with Rafael Nadal, Roger Federer and Dominic Thiem among those not playing in the Japanese capital.
The main talking point surrounds whether the all-conquering Djokovic can continue his march towards a calendar Golden Slam – a sweep of all four majors and an Olympic gold in the same year.
Any notion of a free ride for the Serbian is wide of the mark, though. His side of the draw could see him come up against Andrey Rublev (5), Alexander Zverev (4) and Hubert Hurkacz (7), while Stefano Tsitsipas (3) – beaten by Djokovic in the French Open final – and Daniil Medvedev (2) are among the potential final opponents.
Andy Murray, gold medal winner in 2012 and 2016, faces Canada's Felix Auger-Aliassime in a tricky first-round match.
