Published Sunday, 07 October 2012
McClean in action for the Republic in a friendly against the Czech Republic. (© Getty)
The Derry-born winger picked up the problem during Sunderland's 3-0 defeat to Premier League champions Manchester City on Saturday.
A spokesman for the Football Association of Ireland said McClean reported a "very tight groin" after the game. He will be scanned at his club on Monday.
Meanwhile, in a further injury blow for Republic boss Giovanni Trapattoni, central defender Sean St Ledger has picked up a hamstring injury playing for Leicester City.
He will join up with the squad to have his wounds assessed - however it looks unlikely he will be fit to play on Friday.
The FAI continued: "Sean St Ledger sustained a suspected hamstring injury.
"At the moment it looks unlikely that he will be able to play in the Germany match, but he will report for assessment."
The Republic - who started their bid to qualify for 2014 with an unconvincing 2-1 win in Kazakhstan last month - will take on Group C favourites Germany at the Aviva Stadium this week before heading to Torshavn for the clash with the Faroe Islands next Tuesday.