Jon Flanagan has been drafted in to Rangers' Europa League squad for their clashes against FC Midtjylland.
The full back has been struggling with a hernia injury.
But it is understood he'll be ready to play if called upon.
Polster was a member of the squad for their games against Progres Niederkorn and St Joseph's but Steven Gerrard has made the decision to omit him from the next round of matches - with Flanagan to take his place.
READ MORE: Rangers target Kemar Roofe to leave Leeds United this summer
A lack of homegrown players has forced Gerrard into picking just 22 players instead of the normal 25.
Only Allan McGregor is listed as such among the squad at 37-years of age.
We told how Rangers were drawn against Legia Warsaw or Atromitos if they can make it through against the Danish outfit.
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