Able Friend's season is over after the champion miler suffered a rare tendon injury in his troublesome right front foot and trainer John Moore will request that his horse be sent to Australia for a long period of rest and rehabilitation.

The 1,300-pound chestnut was below his best when clearly hampered by mild lameness when third to Maurice in last month's Longines Hong Kong Mile and when the six-year-old again pulled up sore after trackwork on Monday, MRI scans revealed a strained deep digital flexor tendon in the same foot.

He is done for the season, he is out ... it's very disappointing to have one of the top five horses in the world and to have him sidelined
John Moore

“He is done for the season, he is out,” Moore revealed from Australia, where he is attending the Magic Millions yearling sales.

“He went into the Hong Kong Mile with a bruised sole, we kept him in minor work and the problem didn't resolve itself.

"We got the scans back, got the bad news and now we have to put him aside. It's very disappointing to have one of the top five horses in the world and to have him sidelined.”

Watch: Meet the highest rated horse in the world, Hong Kong's Able Friend

Given the amount of time that Able Friend will be resting, which could be up to six months, Moore believes his reigning Horse of the Year will be better served spelling in Australia, where he said there are also more options for treatment.

“I'll be asking the owner (Dr Cornel Li Fook-kwan) if we can send him offshore and find the best place to rehab him. 

"I hope the (Jockey) club and Dr Li allow us to send him back to Australia. That's the best place for him, I believe.

"Nothing has been arranged yet, he was only scanned on Monday and we had to send the scans off to some experts in Europe to have a very close look at things and to see if he concurred with our findings here, and he did.”

Moore refused to speculate whether this latest setback would spell the end of Able Friend's celebrated career, in which the son of Shamardal has won five Group Ones and collected more than HK$57 million in prize money.

“I've never seen this injury before, so I can't tell you,” Moore said, while admitting that the gelding's enormous frame may have contributed to the condition.

“He is a 1,300-pound animal, so that may be a factor. We just have to get him in a paddock and give him some rehab. Most of all, we need to let the injury cure itself in a nice paddock.”