Trapattoni said on Friday he would finalise his selection before kick-off, deciding whether Liam Lawrence or Aiden McGeady would start on the right wing in a side otherwise unchanged from the team that were minutes from beating Italy last month.
"We must remain calm because it is like the final of the Champions League or the World Cup," the Italian told a news conference. "We will have to avoid nervousness because this is an important game.
"We have to continue to play as we have done until now. Only with this mentality we can play a balanced game against France."
Confirming Fulham's Damien Duff had shaken off an Achilles injury to start on the left, Trapattoni is expected to retain Lawrence on the other flank after the Stoke City player set up the opening goal in last month's 2-2 draw with Italy.
Celtic's McGeady started most of Ireland's unbeaten qualifying campaign but Lawrence's superior set-pieces better compliment Trapattoni's conservative style and could unsettle the French defence.
"I only have one doubt. One (McGeady) is fast and one (Lawrence) plays with different qualities," Trapattoni said.
France, who will be without injured midfielder Franck Ribery, host the second leg in Paris on Wednesday.
Ireland drew 0-0 the last time they were in Paris in a World Cup qualifier five years ago while France won the corresponding fixture 1-0 in Dublin.
"I saw the games in Dublin and Paris ... this match will be for us a new opportunity," said Trapattoni.
"We also have new players now. We can make the difference."
