President Michael D Higgins is to be presented with an Irish jersey when he attends the Croatia match on Sunday.
The President, a lifelong Galway United fan, will be in Poznan for two days as the 25,000 strong Green Army exodus hits town.
Mr Higgins will be presented with the replica top by manager Giovanni Trapattoni in the Stadion Miejski in a private function as 44,000 fans arrive.
Local officials estimate there will even bigger numbers in the city by the time the whistle blows against Croatia tomorrow evening.
The Department of Foreign Affairs said they have had no serious incidents to deal with in the build up to the tournament this week and fans were in good spirits.
One of those, Padraig Walsh from Dublin, dressed in an emerald green jumpsuit complete with ginger beard and leprechaun hat, was ironically doing his best to slip under the radar.
"No photos - sure I wouldn't even tag myself on Facebook," he said.
Minor scuffles involving Polish fans broke out in the main square last night after the competition opener between the hosts and Greece. Quick acting riot police and mounted units swiftly put a stop to it.
Several Polish fans were taken away in police vans. No Irish were involved.