Five-time Olympic champion swimmer Nathan Adrian said he has testicular cancer but is confident of recovery and wants to compete at the 2020 Tokyo games.
In a statement on Twitter on Thursday, the 30-year-old 2012 100m freestyle gold medallist said he expects to be back swimming within "weeks" after starting treatment.
Adrian, who also has four Olympic gold medals as a member of US relay teams, said his illness had been diagnosed early.
"We caught it early, I have already started treatment and the prognosis is good," Adrian wrote.
"I will be back in the water in a few short weeks with my sights fully set on Tokyo."