The 73-year-old Italian says that the 23 men who board the plane for Poland in June will be drawn from those who helped the Republic qualify, and that rules out Best ... despite his fight back from injury.
The Newcastle striker has failed to impress Trapattoni and the Italian came out with an outburst last summer saying Best was not his type of player: "Best does not give me what the other strikers do.
"He doesn't work for the team. He doesn't move like the other strikers.
"He is a lazy player, and I need strikers who give me more."
Best has suffered injury and has just five games to impress the Irish boss ... but Alan Pardew has promised Shola Ameobi that he will be a major part of Newcastle's five-game run in, and Shola has Demba Ba and Papiss Cisse ahead of him.
Where will Best fit in?
It's an uphill battle to get into the team, and certainly not enough time to earn a Euro 2012 place.
Giovanni Trapattoni: "We have 27 or 28 players and it will be a great pity, a great pity, when we have to decide on the 23, to decide on this player or that player.
"The squad is very important to me and they deserve to come with us, they helped us achieve qualification. But I have to decide which players deserve to come with us.
"We are watching games all the time. [Assistant manager] Marco [Tardelli] will be at Sunderland v Wolves at the weekend.
"We have time until a few days before the tournament starts and we can change if there is injury, and then maybe we could do with these extra players.
"I have two or three decisions to make. McCarthy, Coleman, players like that, I have to make a decision and I do not forget them for the next campaign, for the World Cup, but we have to decide the best for now."
Source: FOOTYMAD
