Agar made a stunning Test debut in the Ashes opener at Trent Bridge, making 98 -- the highest score by any Test match No 11 batsman -- in a match Australia lost by 14 runs.

He also played in Australia's colossal 347-run second Test defeat at Lord's.

But, after taking just two wickets in all at a hugely expensive average of 124, Agar was left out of the team that drew the third Test at Old Trafford and hasn't featured since.

And when Australia captain Michael Clarke announced his team Tuesday for the fifth and final Test at The Oval starting Wednesday, Agar was not included, with the tourists already having lost the series at 3-0 down. "Cricket Australia (CA) advises that spinner Ashton Agar will return to Australia this (Tuesday) evening," a CA statement said. "Agar has been unwell for the past week and subsequently a decision has been made to allow him to return early to Australia.

Australia team doctor Peter Brukner added: "Ashton has had a mild viral illness for the past week and needs some time to rest and recuperate. "It has been a long tour and while he has handled the pressure extremely well, we thought it would be a good idea for him to get home as soon possible to have a short break before preparing for the domestic season."

Agar was not included in Australia's squad announced Thursday for the post-Ashes Twenty20 and one-day series. (AFP)