The goalkeeper struggled at set-pieces in defeat to Arsenal.
Ahead of facing Chelsea tomorrow, Postecoglou said: "I think he's seen that there's a challenge.
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"It's something that even I'm struggling with because I watched the Champions League last night and there was a foul given on the keeper straight away. We're trying to get clarity on it."
Asked if he sees the team progressing, he added: "Absolutely, can see them clearly. 20/20. 100%."