SYDNEY (REUTERS) - Australia's Olympic 100 metres freestyle champion Kyle Chalmers has undergone arthroscopic surgery for a shoulder problem but will be ready to compete before next year's Tokyo Games, the 22-year-old's coach Peter Bishop said.

Bishop said Chalmers had been receiving treatment on his left shoulder before a lockdown was imposed due to the Covid-19 pandemic and only recently had the chance to consult a specialist in Sydney.

"He had already had some cortisone injections and then the platelet-rich plasma therapy which was a slow progression," Bishop told Swimming World magazine.

"But then the borders opened between South Australia and New South Wales and so we could actually fly to Sydney to get the opinion of a specialist ... (he) suggested exploratory arthroscopic surgery... and they removed a bursa.

"From initial reports the doctor is very happy with the rest of the structures in the shoulder so there are good signs and my understanding is that rehab will take weeks and not months ... and we should be good to go."

Chalmers, who was due to compete in a virtual short-course meet at the Sydney Olympic pool from Friday, posted a picture of himself on Instagram wearing a sling following the surgery and said: "Rehab starts now, bring on Tokyo 202One."

The Tokyo Olympics will begin on July 23, 2021, after the event was pushed back by a year due to the pandemic.