Despite the assurances of goalkeeping coach Alan Kelly on Wednesday, there were eyebrows raised this morning when the 36-year-old went through a gentle work-out away from the main group at the Municipal Stadium in Gdynia.
Given, who has been nursing knee and calf injuries as well as blistered feet, played just the first 45 minutes of Monday night's friendly in Hungary, his only football since the end of the Premier League season.
But assistant manager Tardelli said: "Today Shay rested because he knows his body. I think he is ready to play.
"Everything is good. He decides to work sometimes yes and sometimes no because he knows."
Given, Ireland's most-capped player, is a key member of Trapattoni's first-choice back five and the Italian would certainly want to be able to include his name as the first on his teamsheet for the clash with the Croatians in Poznan.
However, in Keiren Westwood, he at least has an able deputy and that will be a comfort as the nation waits anxiously for news of the Aston Villa man's fitness.
Trapattoni and his players were back on the training pitch today after an unscheduled day off.
But amid suggestions that an approach from a delegation of players had prompted the alteration in the wake of comments from winger Aiden McGeady following the game in Budapest, Tardelli was adamant the decision came from the manager alone.
He said: "We decide sometimes if it is better to do training or not, and we had a feeling that it was better to stay off. All the decisions depend on the boss.
"The players need to recover after a tough season, but every day we will have training in the morning until the match."
Only three of Trapattoni's players - Given, Damien Duff and skipper Robbie Keane - have appeared in the finals of a major tournament before with Richard Dunne having travelled to the 2002 World Cup finals, but without getting on to the pitch.
For that reason, Trapattoni's vast experience is proving crucial.
Tardelli said: "It is very important because he knows this kind of tournament, and it is very important to speak with the players.
"We also have players with lots of other experience, but he is the same man that was my coach."
The Republic will train in Gdynia once again tomorrow before heading for Poznan and a game they would dearly love to win to get their campaign off to the best possible start.
They will do so with Trapattoni having re-assessed the 0-0 draw in Hungary, which prompted an animated outburst immediately afterwards.
The 73-year-old was initially unhappy with the way his team had coped or, more accurately, failed to cope with the Hungarians' 4-2-3-1 formation and hinted that he may have to dispense with his usual 4-4-2 approach in similar circumstances in the future.
By the time he had arrived in Poland the following day and having watched a re-run of the final warm-up game, his view had mellowed considerably, although it remains to be seen just what approach he will take in Gdansk.
Tardelli said: "Giovanni Trapattoni said it is his duty to change if the team is not good, but I think they played well against Hungary.
"They also played well against Bosnia and against the selection in Tuscany. We are fit.
"We have 23 players and we can change some things. The team against Hungary played very well, and we need to prepare for the match against Croatia in different way. But I think the players are fit."
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