Blackburn, Everton and Liverpool all secured wins on Saturday to put further daylight between themselves and the chasing group. Glenn says this only added to the disappointment of Leeds' penalty leveller.
Man City and West Brom are next over Easter and the boss says that victories are paramount.
"That was the real downer - to come in and see some of the results from teams around us.
"We'd done enough in this performance, from where we were, to have won the game and it would have been a real bonus for us to stay with them.
"We've now got Man City at home and West Brom away and we've got to win both those games.
"If people falter we'll see where it takes us. It's a gradual thing now, over the next five games you've got to see happening around you.
"It's a big task, but we've got to win matches. Performances like this have got to be turned into wins."
Glenn refuses to rule out the possibility of still securing a European place but concedes it is now a 'big task' after the 2-2 at Leeds.