That is why he is so relieved that Michael Carrick is able to return at Stamford Bridge in the absence of John Moncur through suspension, and he explains:
"It really is a different world for ourselves compared to the Chelseas of this world; it is uncomfortable for everybody, not just me, but all the staff.
"Michael Carrick has worked hard this week to build up his fitness and I am hoping it works out that the rest has done him good and that he is really fresh and at the level he was at before the injury, because he was really playing well.
"We certainly need him to be available because of the thinness of our squad which leaves us without any options, particularly with Steve Lomas still injured and because of John Moncur being suspended for these next two games."
Glenn ran the rule over the Blues midweek in their 4-0 demolition of Norwich - the third 4-0 scoreline Glenn had seen in three consecutive days after he watched the reserves and a Hammers XI win by the same margins against Wimbledon and Leyton Orient respectively - and he says:
"It was very impressive, and the game was virtually over after Chelsea scored the first goal - I never felt that Norwich were going to get back into the game, though they tried hard.
"Chelsea played what for me, anyway, was a new system; I've not seen them play 3-5-2 with Frank Lampard sitting behind the front two and with Melchiot, Desailly and Gallas at the back I couldn't see where Norwich were going to break them down."
It is, of course, the second time Frank has played against his old club after leaving for £11m in the summer, and Glenn adds:
"The strength of his game as a midfielder is that he has got this great ability to get into goalscoring positions and take a high percentage of them; from that role on Wednesday night, playing further forward and in the centre of the field, he certainly tucked away his two chances very well."
Chelsea have spent well over £40m in the last year or so and it means trying to second guess what side they will put out, let alone what tactics Claudio Ranieri will use, is nigh on impossible.
"It is one of those bigger teams, bigger clubs that has got a big squad," says Glenn, "and with that Claudio Ranieri has got the facility to be able to rotate and always have you guessing which team he is going to put out.
"It must be wonderful for him to have so many talented players at his disposal - they have got real strength in depth."
But memories of the victory over them at home remain fresh in Glenn's mind, and he says:
"It was a fantastic win for us at Upton Park and we certainly came out all guns blazing, though we obviously came under pressure in the last 20 minutes when we hung on a little bit.
"But we dug deep that night, defended well, and it was a terrific three points for us at an atmosphere-charged game in Upton Park."
A win to add to the three points picked up against Leicester at the weekend would be most welcome but Glenn knows it will be a different kind of game, and says:
"It was the first game where we all said afterwards we had to grind a result out and that is exactly how the game panned out; I would basically agree with everyone who said it wasn't a great spectacle, but as we said before the game, they are difficult matches against sides fighting for their lives.
"Everyone could see that, and they were pretty direct in their methods which was again something we expected - they hit lots of long high balls at Akinbiyi, Scowcroft, and Deane, but I thought the boys at the back dealt with it admirably well, not giving away silly free kicks away.
"We tried to get the ball down and play when we could, but we weren't always able to do that. "It was an important three points, though, and it was nice to be involved in a game like that, shall we say, and actually win.
"We are coming along quietly just in the last few weeks, and that's what we want to continue to do.
"We now face a very tough away game but we are looking forward to it and with eight away games to come in the second half of the season we want to try to pick up as many points as we can to go with the ones that we are more expected to pick up at home."
Meanwhile, on the transfer front, Glenn reiterates that there have been no further developments regarding Paolo Di Canio, and denying that he made any attempt at going for Fabrizio Ravanelli, as has been reported.
"There has been no contact whatsoever with Derby regarding him," he says, "and Paolo is in our squad for Chelsea."