Connections' worst fears have been realised with star Queensland galloper Teronado suffering a potential career-ending injury.

The best case scenario is that the four-year-old will miss up to a year's racing.

Teronado was shaping as a major player in the Melbourne spring in races such as the Caulfield Cup and Cox Plate.

He was a brilliant Doomben winner earlier this month and trainer Bruce Hill took him to Sydney for the George Main Stakes on September 20.

But Teronado finished tailed off last and was found to have an injury to his off hind leg where he had been galloped on.

His leg was sliced and there was major damage to it requiring surgery at the Randwick Equine Centre last week.

Owner Steve Foster said there was a chance Teronado would never race again but it was hoped the galloper would be back next year.

He said Teronado would have two months at the Randwick hospital to recover.

"He will then probably have another two months in a paddock and then Bruce (Hill) will have to start all over again with him," Foster said.

"It is a real pity because we thought this would be his year. But at best he will be out for about 10 months to a year."

"The George Main was one of those stop-start races and Teronado got galloped on."

The four-year-old performed admirably when he travelled south last season, finishing worse than fifth only once in the Australian Derby on a heavy track.

At his previous start he grabbed his first Group One placing when third to Criterion in the Rosehill Guineas to cement Hill's opinion he could mix with with the best.