Manager Andoni Iraola opted to prioritise the 21-year-old McConnell among his midfield options for the League Phase, leaving 33-year-old Wataru Endo out despite the Japan international's experience.
Endo has been an unused substitute in both of Liverpool's opening Premier League fixtures this season, and his omission suggests Iraola is looking to the club's younger options rather than leaning on past service.
Federico Chiesa's absence carries a similar sting. The Italy forward has missed the start of the season through a muscle injury and now finds himself further down Liverpool's attacking pecking order following the summer arrivals of Bradley Barcola and VĂctor Muñoz.
It is a case of déjà vu for the 28-year-old, who suffered an almost identical fate last season under Iraola's predecessor, Arne Slot, only to be added to the squad midway through the campaign after Giovanni Leoni suffered a serious knee injury.
This time, Leoni is one of three injured players Iraola has chosen to include regardless, alongside Conor Bradley and Hugo Ekitike. Leoni, who tore his anterior cruciate ligament, is expected to return to training later this month after almost a year out, while Bradley has been sidelined since a knee injury in January and Ekitike has been out since rupturing his achilles in April. Their inclusion gives Liverpool supporters hope that all three could feature before the League Phase concludes on 27 January 2027.
Academy graduates Luke Chambers and Isaac Mabaya have also been named among 11 defenders on the list. Under UEFA regulations, at least eight of the 25 players in a club's List A must be locally trained, a requirement that shaped some of Iraola's selections. Younger prospects such as Rio Ngumoha and Trey Nyoni miss out on List A altogether, though only because of their age â both remain eligible to play in the competition via List B until they turn 21.
Liverpool begin the defence of their continental ambitions against Atlético Madrid at Anfield on Wednesday night, as they chase what would be a seventh European Cup.
Liverpool's 25-man Champions League squad:
Goalkeepers: Alisson, Giorgi Mamardashvili, Freddie Woodman, VĂtÄzslav JaroĆĄ
Defenders: Joe Gomez, Virgil van Dijk, JĂ©rĂ©my Jacquet, Milos Kerkez, Conor Bradley, Giovanni Leoni, Kostas Tsimikas, Jeremie Frimpong, Ronald AraĂșjo, Luke Chambers, Isaac Mabaya
Midfielders: Florian Wirtz, Dominik Szoboszlai, Alexis Mac Allister, VĂctor Muñoz, Ryan Gravenberch, James McConnell
Forwards: Alexander Isak, Cody Gakpo, Hugo Ekitike, Bradley Barcola