Emma McKeon has been ruled out of the Queensland swimming championships after her coach revealed Australia's most decorated Olympian has been battling a torn muscle under her armpit. McKeon was set to race alongside the returning Cate Campbell in Monday's 100m freestyle heats in Brisbane. But her lane was empty, with the 11-time Olympic medallist's coach Michael Bohl later confirming she had been withdrawn as a precaution. Bohl said McKeon had been managing "a minor tear under her armpit for some weeks" and that the medical advice was to not rush back into competition. McKeon won four golds at the Tokyo Olympics in 2021, and seven medals in total. It was the most by any female swimmer at a single Olympic Games and the joint-most medals across any sport with Soviet gymnast Maris Gorokhovskaya, who achieved the feat in 1952. The championships at Chandler's Brisbane Aquatic Centre are the last meet of the year. The Olympic swimming trials will take place at the same venue in June, some five weeks before the 2024 Games in Paris. Campbell, vying to become the first Australian to swim at five Olympics, has returned to swimming this year from an extended break following the Tokyo Games. She took positive steps on Monday morning, winning her heat in 53.73 seconds, third fastest behind top qualifier Shayna Jack (53.03). Australian Associated Press