Ben picked up a calf injury after just 20 minutes of the 1-0 Premiership defeat against Bolton.
With Chris Perry only just on his way back after eight weeks out it means boss Glenn has five defenders out including four centre-backs - Anthony Gardner (hamstring), Dean Richards (back) and Christian Ziege (thigh) are also missing.
"Ben's pulled a calf muscle and we're not sure how long he will be out," lamented Glenn afterwards. "That's four centre-backs out and it seems to be in the same position all the time.
"We're not sure about Dean at the moment. He's still being looked at. He might have an outside chance of Birmingham but we'll have to wait and see.
"Anthony Gardner is the same, he tore his hamstring against Chelsea and we knew that would be around six weeks."
Glenn Hoddle's defensive nightmare continued as Ben Thatcher hobbled away from the Reebok Stadium on Monday night.