Trevor hurt himself badly in a collision with Sammy Hypia and Glenn explains:
"We found out the extent of the damage when we got back to the dressing room at the end of the game.
"We gave him an X-ray when we got back to London and it reveals a fracture on part of his cheekbone which necessitates an operation today.
"It is all too early to say how long he will be out; I would rather reserve judgment on the length of time for the moment."
But, after a meeting with the medical staff on Monday at Chadwell Heath, Glenn discussed what options there may be to precipitate his return to first team action.
"We are looking into that possibility but we need to speak to the consultant after the operation and we will take his opinion," says Glenn.
"Players have played with masks before to protect them; Paul Gascgoine has, I can remember Mihailovic of Lazio, Edgar Davids, and I think Bunjecevic at Spurs last year played with one.
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"But it is all conjecture at the moment - let's be patient, not jump to any conclusions, and we will have a clearer picture later."
It continues a bad run of luck for Trevor, who was forced to pull out of the last England squad through injury, and Glenn adds:
"He missed the last England game, but hasn't missed a game for us and with due respect to all the players that play for their countries in our squad the only thing that matters, my only concern, is West Ham.
"After the Fredi Kanoute setback, the Don Hutchison setback, Paolo being touch and go for Wednesday, and now Trevor, there are one or two senior players too many not fit at the moment.
"Trevor is an important player for the squad because of how versatile he is.
"On Saturday he has had to play as a striker and that is how he picked up the injury; he turned quickly from a diagonal ball and he and Sam Hypia have collided.
"He was in quite a bit of pain after the game but he had showed his character to play through the game."
Glenn has cleared Hypia of any wrongdoing in the clash, and he reveals:
"I am sure it was an accident; I didn't see Sammy Hypia afterwards but they tell me he went looking for Trevor in the corridors at Anfield and I even think he went onto the coach to try and find him to apologise.
"I have not known him to be anything other than a very fair player - and when you are a central defender, that is hard sometimes.
"It is very hard to be fair in that position but he seems to be able to defend magnificently for Liverpool and still play a very fair game."