Boyle was not available against Aberdeen on Friday after picking up the injury against St Mirren.

"He really now has the focus on the World Cup for Australia," Johnson said.

"We have had confirmation that he is within the group in terms of to see whether he is fit enough to make the final squad. I think he will be okay. I am hopeful for him as well."

Aberdeen-born Boyle has been capped 19 times, scoring five goals, and become a regular starter under national head coach Graham Arnold.

"It is his joint," Johnson added. "There was a bit of inflammation on the joint and that was the bit in question.

"If that goes down and, if it does go down, is he free from pain and free-flowing in his movement, then he is good to go and there is a number of ways that can go down."