Republic of Ireland boss Brian Kerr has not yet heard from Manchester United regarding Roy Keane's latest injury.
Keane broke a metatarsal bone in his left foot following a challenge with Liverpool's Luis Garcia in yesterday's 0-0 Premiership draw at Anfield.
It is thought Keane will miss the next eight weeks, ruling him out of Ireland's last qualifying match in Group Four against Switzerland at Lansdowne Road on October 12.
Keane was already due to sit out the penultimate group game with Cyprus in
Nicosia on October 8 through suspension, but his absence for both matches now places huge pressure on Kerr and Ireland.
The Irish need to win the two games to guarantee themselves a play-off place and the problems are clearly mounting for Kerr with Crystal Palace striker Clinton Morrison and Tottenham winger Andy Reid serving one-match bans.
Kerr said: "I'm disappointed to hear about Roy's foot injury.
"Although we've not yet received medical detail from Manchester United as to the extent of the injury, the nature of it indicates he will be unavailable for our game with Switzerland.
"Whilst you always hope an injury is never as serious as first feared, Roy's loss would be a blow, and I know he will be disappointed to miss the game.
"But we have prepared for the loss of players throughout this campaign, and our focus remains on winning our next two games."
Should Ireland clinch a play-off place, it is likely Keane will also miss what would be a home-and-away double-header in November.
There is even the prospect Keane may have played the last game in the green jersey.
It has long been anticipated the World Cup will be Keane's swansong from international football, but his exit could be brought forward if his Republic team mates do not get the necessary results next month.
With Keane on the sidelines, Kerr could turn to his United team-mate John O'Shea for the anchor midfield role. The 24-year-old was exemplary in that position in a friendly against Italy last month.
