Assuming Australia win the group phase and reach the final on 29th January, Schwarzer will miss four Premier League games and at least one FA Cup tie.
"How long he'll be away is dependent on how successful they are," Hughes told the Daily Mirror.
"Ideally, they'll get knocked out in the group stage. But I've looked at the strength of the group that they're in and that's not going to happen unfortunately.
"They're going to be in the latter stages of the competition so you're looking at three to four weeks."