Champions Spain and under-pressure Italy were the main teams expected to arrive in Poland for the European championship on Tuesday, as the 16 finalists completed their final warm-up matches.
Vicente Del Bosque's side, aiming to become the first team to win back-to-back titles after their victory four years ago, were due to arrive in the Baltic port city of Gdansk on Tuesday evening.
The tournament favourites and world champions take on Italy in Gdansk on Sunday.
Italy, rocked by fresh match-fixing claims that even included a police search of the team hotel and the arrest of several players in the top flight Serie A, were scheduled to fly in on a charter flight from Pisa to the southern city of Krakow.
The Republic of Ireland arrived in Gdansk in the small hours of Tuesday direct from Budapest, where they took on Hungary in a friendly match on Monday night. Croatia, the final Group C side, arrived on Tuesday morning.
Portugal arrived late on Monday night in the western city of Poznan to prepare for their opening Group B match against title contenders Germany in the Ukrainian city of Lviv on Saturday.
German talisman Bastian Schweinsteiger successfully came through training on Monday after picking up a calf injury during his club Bayern Munich's Champions League final defeat to Chelsea last month.
Ireland's 0-0 draw with Hungary was Giovanni Trappatoni's 14th game without a defeat and, with veteran goalkeeper Shay Given coming through the match unscathed after an injury scare, will boost the side in tough group.
Co-hosts Ukraine, though, were playing down concerns about their readiness after a friendly defeat to Austria.
Veteran star Andriy Shevchenko insisted: "Our preparations for the Euro are going according to the plan and the results of the friendlies are not really important. Neither the 4-0 win over Estonia nor the defeat at Innsbruck count for anything."
Instead, the 35-year-old former European player of the year, who bows out of international football after the tournament, said Ukraine's opener against Sweden on June 11 will show whether they are physically and mentally ready for the tournament.
Ukraine also take on England and France in Group D.
England were expected to arrive at their Krakow base on Wednesday, while France were due in Donetsk, Ukraine, after their friendly match against Estonia in Le Mans on Tuesday evening.
France coach Laurent Blanc has called for more consistency in his side's play, after "Les Bleus" demonstrated some thrilling football in the first-half of their 2-0 defeat of Serbia last Thursday before their level dipped.
"The match will serve to help the team and the players pick up speed but also to keep them fresh because we'll need all our weapons (for the opening game against England) on June 11," he said on Monday.
"We need to win this match and be more consistent in our play. Against Serbia, we were only consistent for 60 minutes. I hope we'll do it for even longer and that we won't have any physical problems."
Yann M'Vila is a doubt with an ankle injury, with Marseille midfielder Alou Diarra poised to take his place both against Estonia and England.
England have been hit by a succession of injuries, forcing Frank Lampard, Gareth Barry and Gary Cahill to withdraw. They are also without Manchester United star Wayne Rooney for the first two group matches through suspension.
Rooney's Old Trafford team-mate Rio Ferdinand, meanwhile, moved to play down claims from his agent that coach Roy Hodgson had shown a lack of respect for not picking the defender as Cahill's replacement.
"Just so we don't get twisted erei'll be in a pub somewhere supporting England this summer! Love the lads!" tweeted the former England captain.