Defenders Mike Nawrocki, Alexandro Bernabei and Yuki Kobayashi were left out of Celtic’s Champions League squad.
Polish centre-back Nawrocki is out with a hamstring problem and faces a six-week lay-off along with fellow defenders Cameron Carter-Vickers and Stephen Welsh.
The latter pairing made the 25-man squad with home-grown Welsh a potential factor in the decision.
Celtic have since brought in Nat Phillips on loan from Liverpool to sort out their injured list of defenders, while fellow summer signing Gustav Lagerbelke is also in the pool.
Japanese centre-back Kobayashi is expected to return to fitness soon after an ankle injury but is not in the squad.
Bernabei has played twice this season but was left out of Liam Scales’ possible back-up for left-back Greg Taylor after an impressive performance at center back in the recent win over Rangers.
There is also no room for goalkeeper Benjamin Siegrist, midfielder Kwon Hyuk-kyu and summer recruit Marco Tilio, who arrived at Celtic through injury, as well as James McCarthy, who last played in October last year.
Celtic begin their European campaign in Rotterdam next Tuesday against Feyenoord, and will also face Lazio and Atletico Madrid in their group.