Australia's defending 100m freestyle champion James Magnussen will miss July's World Championships in Russia through injury.
The 24-year-old Commonwealth gold medallist needs to have surgery on his left shoulder.
"All indications from our medical staff are that surgery is the best option," said head coach Jacco Verhaeren.
"This will give him more time to have the operation and start rehabilitation before preparing for Rio."
Magnussen, who won silver at London 2012, added: "We, as a team, have explored every possible avenue to allow me to compete but unfortunately surgery is the only viable option if I am to be fit for the 2016 Rio Olympics.
"I will now focus all my time and effort on preparing for the Olympics next year. I am looking forward to regaining full strength in my shoulder and getting back to my best performances."