Last year's Gr.1 Auckland Cup (3200m) winner Ocean Billy is facing a lengthy stint on the sidelines after suffering a tendon injury.

Rotorua owner Bill Pomare, who had trained Ocean Billy in New Zealand before sending him to Sydney, said he had received a call from trainer Chris Waller telling him the bad news on Thursday afternoon.

"He trialled this week and ran third,” Pomare said. “James McDonald rode him and said he came up underneath him nicely. But he did get cast in the box about 10 days ago so whether that had something to do with it, I don't know.

"Chris said he's not lame on it but it has swollen up. He will box him for another four weeks until the swelling goes down and then he'll come home.

"It will take him a few months to get over it and then several months more for a slow recovery and to strengthen it again. It will probably take him 10 months before pressure can go on the tendon again. I'll see how he comes up then decide what we do with him.

"He could still come back from this. I had a horse years ago that had done a really bad tendon injury and I nursed him back. I did a lot of riding around the roads with him and he came back and never broke down again so it can be done."

Pomare said the news was the latest blow for Ocean Billy after the death last week of his part-owner in the stayer, Peter Ludgate.

A winner of seven of his 24 starts for Pomare, Ocean Billy transferred to Waller for a fruitless Melbourne spring campaign in which he was unplaced in the Gr.1 Caulfield Cup (2400m) and Gr.1 Melbourne Cup (3200m) at Flemington.