Here are nine notable absentees from confirmed European squads this season. To keep things simple, only one key player from any team will be looked at closely.
Federico Chiesa
Liverpool, Champions League
Liverpool manager Arne Slot has preferred 17-year-old Rio Ngumoha to the Italian international, despite suggesting Chiesa would play a more prominent role this term.
The former Juventus and Italy star, who made 14 appearances last season, has started 2025/26 brightly, including a decisive goal in a 4-2 win over Bournemouth.
Ngumoha, to his credit, impressed with a last-minute strike against Newcastle, a match Liverpool won 3-2, signalling the club’s faith in youth.
Gabriel Jesus
Arsenal, Champions League
The Brazilian forward’s absence is understandable, given he is still recovering from a knee injury, compounded by Arsenal bolstering their options over the summer.
That said, Rayan Cherki made Manchester City's squad despite expecting to miss two months (most of the upcoming matches) through injury.
Jesus appears to have fallen down Mikel Arteta’s pecking order in north London, with Kai Havertz moving into a more central position.
Ross Barkley
Aston Villa, Europa League
Despite finding form again at Aston Villa, following his move from Chelsea and spells at Nice and Luton, the former Everton midfielder hasn't made the cut.
Barkley impressed for Villa again last season, joining the club on a permanent deal after Luton's relegation, but new signings Harvey Elliott and Jadon Sancho are seemingly preferred by manager Unai Emery.
The 31-year-old is left to focus solely on domestic football for Villa this season -- at least until the New Year.
Arkadiusz Milik
Juventus, Champions League
Though not a huge shock for anyone familiar with Serie A, Milik's absence is perhaps a surprise for those who remember his best years at Napoli and Ajax.
The Polish striker scored just four goals in 32 league matches for the Old Lady last season, and has been linked with a move away.
Milik faces stiff competition from Dusan Vlahovic, the club's leading goalscorer last term, as well as promising Turkish striker Kenan Yildiz and Canadian star Jonathan David.
Mathys Tel
Tottenham, Champions League
The omission of Tottenham’s £30m summer signing from Bayern Munich is a curious one.
Spurs brought in a hoard of talent over the summer, including Mohammed Kudus, Xavi Simons and Randal Kolo Muani. But Tel’s exclusion has raised eyebrows, not least because it appears to be the product of poor planning.
Caught out by 'homegrown' (club-trained) player rules, Thomas Frank was forced into a difficult choice -- and it is the 19-year-old French forward, rather than 26-year-old loanee Kolo Muani, who has made way.
Omari Hutchinson
Nottingham Forest, Europa League
Forest gave us perhaps the most surprising omission, given Hutchinson was signed over the summer for a club-record fee of £37.5 million.
Homegrown player limitations may explain part of it, though there are suggestions that Hutchinson's omission is symptomatic of an ongoing rift between club owner Evangelos Marinakis and manager Nuno Espirito Santo.
Whatever the case, Forest fans will be disappointed to see their marquee man sidelined on the continental stage.
Facundo Buonanotte
Chelsea, Champions League
Chelsea brought in the Brighton forward on loan, only to leave him out of European competition, which, like others on this list, is a move that has raised eyebrows.
The club's decision to sign Buonanotte was a strange one anyway, given there is no obligation to make the deal permanent.
We are then forced to assume Buonanotte has been earmarked for domestic duties, a puzzling strategy that underlines Chelsea’s complex squad-building approach.
Shin Yamada
Celtic, Europa League
New Celtic signing and Japanese international Yamada has played in three of four Premiership matches this season, but has missed out on the club's Europa League squad selection.
Perhaps the late summer signing of Kelechi Iheanacho signals that Celts boss Brendan Rodgers was seeking more depth up top, leaving Yamada to bide his time domestically.
Jamaal Lascelles
Newcastle, Champions League
Lascelles, who did not feature at all for Newcastle last season, is another predictable omission.
But, given his perceived ability, it could be seen as a shame to omit a player who might still impress for a club lower in standing than the Magpies.
That said, it is believed the Saudi-backed club are looking to sell Lascelles abroad -- with Saudi Arabia, Turkey and Greece's transfer windows, among others, still open.
Honourable mentions
Yves Bissouma, Radu Dragusin, James Maddison (all Spurs); Oleksandr Zinchenko, Jota Silva, Taiwo Awoniyi, Angus Gunn (all Forest); Raheem Sterling (Chelsea)