Ireland captain Robbie Keane has been ruled out of tomorrow night's World Cup qualifier against Germany after succumbing to an Achilles injury.

The 32-year-old was unable to play a full part in training in Malahide this morning and the decision has been taken that he will not be involved in the game at the Aviva Stadium, although he has not given up hope of making Tuesday's trip to the Faroe Islands.

Keane, who is understood to have aggravated the long-standing injury in a training ground challenge with defender Paul McShane earlier this week, did not train yesterday morning either.

Assistant manager Marco Tardelli was initially confident Keane would be able to play tomorrow, however that possibility evaporated this morning, leaving manager Giovanni Trapattoni to draw up another plan.

The Italian had been expected to field the LA Galaxy forward, who has 54 senior international goals to his name, as a lone striker against the Germans.

That indication had prompted a media discussion about Keane's ability to perform that role and an assessment of the relative merits of the other frontmen in the squad, Shane Long, Jon Walters and Simon Cox and their suitability for the task.

Trapattoni is expected to employ a three-man central midfield combination in a bid to deny Germany time and space in the middle of the park.

However, Tardelli hinted that one of the wide positions would be filled by a second striker.

If the 73-year-old Trapattoni opts for that approach, he now faces a decision of which of his remaining frontmen to deploy furthest forward with Long boasting speed and strength, Walters perhaps the most physical of the three and Cox able to stretch defences with his pace.

Keane, whose last-gasp strike in Ibaraki 10 years ago secured a famous 1-1 World Cup draw with the Germans, was in line to win his 122nd cap against Joachim Low's men.

His absence means Trapattoni will be without all four of the men who have formed the backbone of his squad for the last four and a half years with Shay Given and Damien Duff having retired from international football and Richard Dunne still working his way back to fitness.

It is the first competitive game Keane has missed since the 2-1 Euro 2012 qualifier victory over Armenia in Dublin in October last year after emerging from a 2-0 win in Andorra with an adductor muscle injury.

Trapattoni has had a difficult week as the casualty count has mounted with Sean St Ledger, Glenn Whelan, Kevin Doyle, James McClean and now Keane having all joined Dunne on the sidelines.