"I'll be back, I don't think it's that serious," he maintained last night.
"Obviously my body hasn't done this type of serious training for a very long time and maybe that had something to do with it. But I'll be playing again this season - or even this spell, I'm trying to be positive. It's a minor setback, and hopefully I'll be fit for next Friday - if not, then as soon as possible."
Coast coach Lawrie McKinna said the club would make decisions about Bosnich's future once the extent of the injury was known.
"We hadn't even sat down and talked about the future," he said. "He was keen to get through this spell, and he does train hard. Once we know on Monday we'll look at it - it could be a couple of weeks or it could be longer term."