In addition to his first choice pairing of Alan Stubbs (groin) and Marc Rieper (ankle) having no better than "60-40" chances of playing, their immediate deputy, Enrico Annoni, has flu symptoms.
Venglos has a contingency plan for his defence which may see his most influential midfielder, Craig Burley, drafted into emergency defensive service. Late fitness tests on Stubbs, Annoni and Rieper will determine whether that occurs, but, if the latter plays, it could well be only delaying the inevitable for the Danish international, who is understood to need surgery.
Celtic will at least have the Frenchman Stephane Mahe available, as well as the versatile Tom Boyd. Venglos said: "Whoever needs to come in will play to their best of their qualities, but it is a problem that all of the players under 100 per-cent all play in the same position of the pitch.
"It is a pity that it had to happen now, but we have adaptable utility players like David Hannah and Craig Burley who can do what we need if required."
Jackie McNamara is also available after injury, but Venglos is mindful that the Scotland wing-back has been without competitive action for two months and he is unlikely to be risked from the start.
The FC Zurich squad includes the 25-year-old Trinidadian international striker Jerren Nixon, who had an 18-month spell in Scottish football with Dundee United in the mid 1990s, and the South African forward Shaun Bartlett.Reuse content