The in-form striker - nine goals in his last 11 appearances,including a hat-trick and the Premiership's 10,000th goal - had fluid drained from his troublesome ankle on Monday.
Boss Glenn revealed that Les had been playing at 75 per cent fitness since picking up the injury against Arsenal a month ago and that he would be assessed in training today.
"Les is the main concern on the injury front," confirmed Glenn. "He's had some fluid taken away from his ankle, Achilles area on Monday.
"That is settling down but he's not trained this week. We'll have to see how he shapes up on Friday morning.
"The fact he hasn't done anything suggests he might miss out but we'll give him an opportunity to try it. I'd say he was no more than 50-50.
"Les has been playing with that injury and he's probably only been 75 per cent fit. He's not been able to train as we would have liked over the last couple of weeks.
"But coming into this stage of the season where we've so many games we're going to have to use the squad anyway. We'll look at what he can do and decide whether Saturday is good for him or not."
Goran Bunjevcevic (thigh) and Christian Ziege (foot) are both improving but not expected to return on Saturday.
Steffen Iversen continued his return from injury in Thursday night's friendly at Stevenage Borough but Stephen Clemence has suffered a slight setback on his comeback trail.
Glenn revealed: "Steve had three or four reserve games and looked like he was ready to come back into the fray but picked up a slight groin strain so had three or four days off. He's also had the flu - it's been one of those frustrating times for him."
Glenn Hoddle rates Les Ferdinand as 'no more than 50-50' to be fit to face Ipswich Town on Saturday.