Accusations against Manchester United shot-stopper David De Gea have thrown Spain's preparations into turmoil as they prepare to face the Czechs in Toulouse in Group D.
Elsewhere, the battle to survive the pool dubbed Euro 2016's 'group of death' begins when Ireland play Sweden at the Stade de France, before Belgium play Italy in Lyon in Group E.
Vicente del Bosque's Spain are chasing a treble of European championship titles when they start their campaign against the back-drop of their off-field woes.
De Gea is vying with 167-cap veteran and captain Iker Casillas, a hero of Spain's three consecutive major championship triumphs between 2008 and 2012, for a starting place.
The 25-year-old has strongly denied allegations that he organised a party at which two women were forced to have sex with two footballers. The storm has taken the focus of Spain's arrival in France away from football.
The team say they are backing De Gea but he will not find out if he has a place until just before the game.
Spain have won their last three meetings with the Czech Republic and Del Bosque's side are on an eight-game competitive winning streak.
Spain have a crop of young talent coming through and Andres Iniesta says the team has the quality to go all the way to the July 10th final.
"Times change and players move on but it's always about quality and we have tons of that - enough to do well in our objective of retaining the trophy," said Iniesta, whose goal won the 2010 World Cup final.
Belgium's star-studded attack will come up against Italy's dogged defence, but Manchester United's Marouane Fellaini says his team have the weapons to make a winning start.
Marc Wilmots' Belgium have shot up the world rankings from 66th in 2009 to second coming into the European Championship finals and are amongst the favourites in France.
Now the Red Devils boss is urging his side to live up their billing as favourites in the crunch Group E clash as Italy goalkeeper Gianluigi Buffon prepares to play in his 11th tournament.
"A win would give us confidence, but a defeat would shake everyone up, so we have to be on form right from the outset," said the 47-year-old Wilmots.
"We need our '12th man' behind us, if we are here it's because of the Belgium supporters being behind us through the good and bad, they are the heart and soul of the team."
His counterpart Antonio Conte expects a battle royal.
"There will be warriors on the pitch for both sides, these games are so important you feel the breath on the back of your neck," said the Italy's boss, who steps down after Euro 2016.
The Republic of Ireland have the task of containing Sweden's superstar striker Zlatan Ibrahimovic at the Stade de France.
Irish manager Martin O'Neill says his side have nothing to fear, but Ibrahimovic comes into the match on the back of dazzling form.
Now 34, the Manchester United target appears to be getting better with age having scored 50 goals in all competitions in his final season with Paris Saint-Germain.
The Irish qualified for Euro 206 by beating Bosnia and Hercegovina in a play-off and defeat in their first game would present them with an uphill task as Belgium, then Italy follow.