Austria captain Marc Janko is suffering with an ankle problem ahead of Friday's Euro 2012 qualifier against Belgium.
The FC Twente striker is in prolific form, scoring 14 goals in 25 games in the Eredivisie this season, and would be a big loss for head coach Dietmar Constantini.
Janko was forced to withdraw from the Austria squad that lost a friendly to the Netherlands last month but hopes to overcome a ankle ligament injury to face Belgium in Vienna.
The 27-year-old scored 39 goals in 34 games to fire FC Salzburg to the Austrian Bundesliga title in 2008/09 and finished behind Samuel Eto'o and Diego Forlan in the running for the Golden Shoe.
Austria, who are second in Group A, five points behind leaders Germany, drew for 4-4 with Belgium in the corresponding fixture earlier in the campaign.