Skipper Robbie Keane and experienced winger Aiden McGeady trained with their Republic of Ireland team-mates on Tuesday morning after jetting into Dublin.
The pair arrived from Los Angeles and Moscow respectively on Monday and were out on the training pitch at Gannon Park for the day's first session.
They were joined by Aston Villa defender Ciaran Clark, who was drafted in when it became clear that Sean St Ledger's hamstring injury would rule him out of the World Cup qualifiers against Germany and the Faroe Islands.
There was no sign of keeper Kieren Westwood, Giovanni Trapattoni's number one after Shay Given's retirement from international football, but assistant manager Marco Tardelli later revealed the Sunderland man had been rested and was training in the gym.
Ireland will be without five key men for Friday night's clash against Group C favourites Germany with St Ledger, Richard Dunne, Glenn Whelan, James McClean and Kevin Doyle all missing through injury.