The two most noteworthy chances fell to Les Ferdinand and Glenn hinted afterwards that he feared the worst with not taking advantage of first half superiority.
"I think that's the key to the game for us," reflected Glenn. "We haven't dominated a game like that for 45 minutes this season - it was an eerie sort of a feeling to come in at 0-0.
"You think to yourself that you've got to respond to that, they can't play as poor or we can't stop them as much as we did. Not getting the goal was always going to be a slight problem to us I felt.
"If we'd have scored in that period of time I think we would have gone on and won the game. They came out with a bit of a spring in their step and got what I felt was a poor goal to give away. One that shouldn't have ended up in the back of the net."
Glenn admits that he was disappointed that the team did not respond so well in the second half as a unit.
"The two keys for us was playing so well in the first half, dominating and not scoring and not responding like we should after that - as a team, collectively.
"There was still some good football played, there was still some good chances created and a lot of pressure on them at the end."
Glenn says that not scoring during a lengthy spell of first half pressure cost us dear against Southampton at St Mary's.