In the US, it is a fully fledged professional sport with about 5 million players and a profile growing so fast that tennis superstars including Nick Kyrgios and Naomi Osaka, and NFL great Tom Brady have invested in pickleball leagues. Tennis Australia is planning to offer the sport at clubs around Australia, though the competition between pickleball and tennis has produced some tension in the US as the sports compete for players and facilities. Read more here.