The mercurial former Leeds man has played through the pain-barrier in recent weeks and could finally succumb to the injury for this Sunday's FA clash with Portsmouth and Australia's international friendly three days later.
"If you come here before training you can see Harry is still having treatment on it every day," Houllier said.
"He suffered a recurrence of the ankle problem and it's not totally healed. He felt it a bit against Manchester City this week."
"It depends on the doctor whether or not he is going to go with Australia or not."