Spring carnival plans remain clouded for Australian Cup winner Spillway.

Co-trainer Tom Dabernig confirmed Spillway had sustained a minor leg injury which had put his spring preparation in some doubt.

"It's sort of nothing serious long-term, he's back in work at the moment but he's just coming along slowly," Dabernig told Melbourne Radio station RSN.

"Hopefully all being well we'll have him back for the spring, if not he'll sit back and wait then probably for the autumn."

Spillway won the Group One Australian Cup at Flemington in March a photo-finish from stablemate Extra Zero.

He then finished fourth in the $4 million Queen Elizabeth Stakes won in dominant fashion by stablemate Criterion.

Dabernig said the stable's decision on Spillway's spring would be guided by the horse's progress.

"At the moment he's doing a slow, steady build-up. He's under saddle and the test will be when we start the early stages of galloping, and he'll sort of tell us what we can do with him."