There may still be months to go before the squads are announced, but here we pick one possible star from each contender. Use #U21EURO to tell us who you expect to impress this summer.
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England: Marcus Rashford (Manchester United)
Though mostly used off the bench by José Mourinho this season, striker Rashford – who so memorably burst onto the scene in last term's UEFA Europa League round of 32 – continues to frighten Premier League defenders with his electric pace and direct style whenever given the chance. Whoever is England manager in Poland this summer will surely be desperate to have the Manchester United teenager at their disposal.
Poland: Piotr Zieliński (Napoli)
Zbigniew Boniek is a huge fan of a footballer considered one of Poland's biggest talents in years. Brought to Italy by Udinese aged 16, Zieliński is a classic playmaker and last summer he became the third-most-expensive Polish player ever (behind club-mate Arkadiusz Milik and Paris's Grzegorz Krychowiak) when he joined Napoli. Part of Poland's UEFA EURO 2016 squad, he has 23 senior caps.
Slovakia: Martin Chrien (Viktoria Plzeň)
The Banska Bystrica-born midfielder loves to get forward and has an eye for goal which could be crucial for Slovakia's chances. He scored three in his first three games on loan at Ružomberok at the start of this season and has since returned to Plzeň, where coach Roman Pivarník has been impressed with his performances in recent friendlies.
Sweden: Alexander Isak (AIK)
In March 2016, few people beyond his local high school in Solna had heard of Alexander Isak. That April, the then 16-year-old made his Allsvenskan debut for AIK, scoring in a 2-0 win at Östersund. The forward's subsequent exploits have included two goals in a high-pressure derby against Djurgården and becoming the youngest player to score for Sweden, at 17 years and 114 days, in a friendly against Slovakia on 12 January.
FYR Macedonia: Enis Bardi (Újpest)
Bardi already has eight goals in 18 Hungarian First League appearances this term and, despite being deployed as a midfielder, is the joint-leading scorer in the division. He also found the net twice for his country during qualifying and is central to all their attacking play.
Portugal: Gelson Martins (Sporting CP)
With dazzling dribbling skills, quick thinking and impressive acceleration, Gelson – the latest top-end winger from Sporting's renowned academy – began to impress last season but really announced himself by causing Real Madrid's Marcelo all sorts of problems on matchday one. He already has eight Portuguese Liga assists this campaign and made his full international debut in October. A dead cert for Poland unless Fernando Santos needs him at the FIFA Confederations Cup.
Serbia: Andrija Živković (Benfica)
Serbia's youngest ever international and star of their 2015 FIFA U-20 World Cup win. A left-footed winger, Živković was a Partizan regular (and eventually captain) for three seasons before being snapped up by Benfica last summer. He is still only 20 and Siniša Mihajlović, who gave Živković his Serbia debut, is convinced he will go all the way. "This little kid will be a big player."
Spain: Marco Asensio (Real Madrid)
A breathtaking solo goal against Sevilla was the latest confirmation of Asensio's astonishing talent, the Madrid winger having been one of the star players at the 2015 UEFA European U19 Championship. Possessing astounding dribbling skills and a great footballing brain, he looks certain to sparkle again for Spain in Poland.
Czech Republic: Patrik Schick (Sampdoria)
The overall top scorer in qualifying with ten goals – not to mention four assists – Schick has subsequently been involved in two of the senior side's European Qualifiers. The 20-year-old, who has an especially effective left foot, joined Sampdoria from Sparta Praha in the summer and struck against Juventus on his first start for the club.
Denmark: Kasper Dolberg (Ajax)
Already capped at senior level, the teenaged forward struck on his Ajax debut in a UEFA Champions League qualifier in July and also found the net twice during the UEFA Europa League group stage, having been discovered by John Steen Olsen – the same scout who brought Zlatan Ibrahimović and Christian Eriksen to Amsterdam.
Germany: Matthias Ginter (Borussia Dortmund)
Ginter represents tremendous value for two key reasons: firstly his versatility – he is adept at centre-back, at right-back and as a central midfielder – and secondly his experience. Indeed this would be the 2014 FIFA World Cup winner's third U21 final tournament (potentially the same for Emre Can).
Italy: Domenico Berardi (Sassuolo)
The knee problem that forced Berardi to miss most of the first half of this season probably only delayed his full international debut, but the winger is nonetheless expected to spearhead Italy's bid thanks to his creativity and lethal left foot. He has already scored over 50 Serie A goals and shone in Europe, registering five times in four UEFA Europa League qualifiers before his injury.