Team USA is the favorite to top the medal tally with 621 athletes competing.
They are overall Olympic medal chart leaders with 2523 medals.
China has claimed 608 medals in the history of the Olympics. While 237 are gold. China has the world's top athletes in diving and wrestling.
While the use of Russia's name is banned, athletes will still compete. More than 300 athletes will be representing ROC at Tokyo.
Host nation Japan is predicted to have its best outing at Olympics this year. The medal prediction is 30 gold medals, a feat Japan has never reached.
367 British athletes will compete in Tokyo. While the nation finished at second position in Rio, it's predicted to be at the fifth position in the 2020 Olympic games.