Dunk, 31, has been an ever-present for Roberto De Zerbi’s impressive Brighton this term but was forced to miss the clash with Greek champions AEK Athens.
The defender also played for England against Scotland at Hampden Park last week and then swiftly played a key role in Brighton’s 3-1 win at Manchester United last Saturday – where he is believed to have picked up the injury.
Dunk struggled with a neck and back injury towards the back end of last season and it seems injury has prevented him from making his first ever outing in the Europa League, with De Zerbi not prepared to take any risks on his star man.
There was however a a full debut for Ansu Fati as De Zerbi made seven changes in total to the team that beat Man United 3-1 at Old Trafford.
Goalkeeper Jason Steele, defender Jan Paul van Hecke, experienced midfielder Pascal Gross, and Japan international winger Kaoru Mitoma all retained their spots.
Teenage striker Evan Ferguson – who has been managing a knee injury since his hat-trick against Newcastle just prior to the international break – was not in the squad.
Joel Veltman, Dunk (injured), Tariq Lamptey, Mo Dahoud, Simon Adingra, Adam Lallana and Danny Welbeck all dropped out from the Man United win, with veteran James Milner, left back Pervis Estupinan, winger Solly March, Billy Gilmour, Fati, Joao Pedro and defender Igor Julio (debut), all coming in.
Brighton XI: Steele, Milnr, Van Hecke, Igor Julio, Estupinan, March, Gilmour, Mitoma, Gross, Fati, Joao Pedro Subs: Verbruggen, McGill, Lamptey, Webster, Dahoud, Lallana, Welbeck, Baleba, Adingra, Veltman, Bounanotte, Hinshelwood
AEK Athens XI: Stankovic, Szymanski, Amrabat, Jonsson, Garcia, Gacinovic, Araujo, Pineda, Mitoglou, Hajsafi, Sidibe. Subs: Athanasiadis, Theocharis, Mohammadi, Zuber, Rota, Pronce, Eliasson, Mantalos, Galanopoulos, Pizarro