While Ebere Eze is now being sold to Crystal Palace, a proposed move to Liverpool for Guehi is being delayed as Glasner puts his foot down.
After last night's 1-0 win against Fredrikstad, the Austrian insists Guehi must stay for another week: "We have to, especially for the second leg.
"No injured player will come back and we cannot register anyone so we have to keep him.
"We already rested Chris Richards and Ty Mitchell who had small problems. There is no other choice than keeping Marc for these games. He knows it, everybody knows it. If we want to compete in all of these competitions we need players, that is pretty clear."
Glasner added, "If Marc leaves maybe I will try my boots because I was a centre-back. We have to act. It’s Crystal Palace’s future and we need to add numbers.
"We are very, very late to find replacements. I think we could behaved much better than we did. It’s not the best way to start the season. I think we are below the edge."