Roberto Martinez has given Cristiano Ronaldo his full backing since taking over as Portugal coach and he will be hoping that faith helps provide the nation a second European Championship title, while Georgia make their first major tournament appearance in Group F.
Ronaldo has taken his men's international records to 206 appearances and 128 goals since Martinez took charge.
The 39-year-old is set to break more records in Germany this summer in his 11th major tournament, including appearing at a record sixth European Championship, as he bids to extend his all-time leading mark of 14 goals in the competition.
He finished as the second top goalscorer in Euro 2024 qualifying, allaying some fears that switching to the Saudi Pro League would hinder his efforts for Portugal.
Ronaldo was dropped from the starting line-up by previous boss Fernando Santos during the knock-out stage of the 2022 World Cup, as Portugal suffered a shock quarter-final defeat at the hands of Morocco.
But he has reestablished himself as the team's talisman, despite Portugal also boasting the attacking talents of Bruno Fernandez, Bernardo Silva, Diogo Jota and Goncalo Ramos.
"Cristiano is a unique player in the world, with the highest number of international caps," Martinez said early in his reign after being appointed coach following the Qatar World Cup, where he oversaw Belgium's disappointing group-stage exit.
"The experience he has for the dressing room is very important.
"All players have an important role. The younger ones due to their willingness to play and players like Cristiano Ronaldo, Rui Patricio and Bernardo Silva bring experience.
"It's important to have a complete dressing room."
In spite of his advancing years, Ronaldo will not be the oldest player in the squad.
His former Real Madrid team-mate Pepe, 41 and now playing for Porto, has also been called up because of his "important role in the dressing room", said Martinez.
Ronaldo's Al-Nassr teammate Otavio will be missing through injury, with Manchester City midfielder Matheus Nunes called up as his replacement.
Portugal will be red-hot favourites to progress from Group F, but Ronaldo will be among those who know how tricky a seemingly easy pool can be, after the Portuguese scraped into the knock-out phase with group draws against Austria, Hungary and Iceland en route to the 2016 title.
Martinez's men kick off their campaign against the Czech Republic in Leipzig on June 18, before facing Turkey four days later in Dortmund and completing the group stage by taking on Georgia in Gelsenkirchen on June 26.
Portugal are bidding to become only the third nation to lift the trophy twice in the space of three editions or fewer, after Spain in 2008 and 2012 and West Germany in 1972 and 1980.
They suffered a disappointing 1-0 loss to Belgium in the 2020 last 16.
- Debutants Georgia relying on Khvicha -
Georgia make their major tournament bow relying on star man Khvicha Kvaratskhelia, against the backdrop of turmoil and political violence back home.
The only debutants at this year's event came through the play-offs with a penalty shoot-out triumph over former European champions Greece.
The 24-team format gives smaller teams like Georgia hope of reaching the knockouts, with one win potentially enough to secure one of the best third-placed berths.
Kvaratskhelia was part of Napoli's miserable Serie A title defence this season, but remains Georgia's key man after scoring four goals in qualifying.
"Football for me is like my life. It's so simple to say but football is my life," he said in April.
Mass protests from pro-European opposition broke out in Georgia in April after the government, led by the Georgian Dream party, introduced a controversial "foreign influence" bill.
The Czechs will be favourites to progress alongside Portugal and have often impressed at previous Euros, including three years ago with a run to the quarter-finals which was ended by Denmark.
Patrik Schick will again be expected to provide the goals after finishing as joint-top scorer at Euro 2020 with Ronaldo, after enjoying a memorable season at Bayer Leverkusen as they won the Bundesliga-German Cup double.
Turkey were widely tipped as potential dark horses for the title last time but slumped to a dreadful group-stage exit.
Vincenzo Montella's team, led by Hakan Calhanoglu and hoping for a breakthrough performance from Real Madrid starlet Arda Guler, will be out to prove a point.