Hannover have warned Celtic to forget about signing Szabolcs Huszti in the January transfer window.
Celtic chief Gordon Strachan admitted last week that the Hungarian international is among his transfer targets.
The 25-year-old's contract expires in the summer, fuelling talk that he could be sold next month rather than be allowed to run down his deal and then leave on a free transfer.
However, Hannover are battling against relegation and coach Dieter Hecking insists they will not sell Huszti as they need him to achieve survival in the Bundesliga
"We might loan out a few players once the transfer window merry-go-round starts after Christmas," said Hecking.
"But there is one thing I can say for sure and that is that we will not sell Szabolcs Huszti."
Hannover chairman Martin Kind believes the sale of Huszti, who is their top scorer with three goals, could have an impact on their bid to avoid the drop.
Kind said: "It would be the wrong decision if we let Szabolcs leave for a multi-million pound fee and then got relegated.
"If an offer comes in for him, it is down to Hecking and our director of football Christian Hochstaetter to calculate his value as a player.
"And they will have to consider the question of how to replace him."
Meanwhile, Koki Mizuno hopes to stay in the Celtic side for the Old Firm clash with Rangers on Saturday.
The Japanese midfielder scored in the 3-0 win at Falkirk last Sunday in what was his first start since signing from JEF United in January.
The 23-year-old is now hoping he has done enough to keep his spot in Strachan's side.
"I hope I can play in the Old Firm game but I know that match is totally different from the Falkirk game," noted Mizuno.
"I know how important the Old Firm game is, how difficult they are to play in and what it means to our fans to win.
"If I can even get a chance to show what I can do I will give it my very best."
PrideMizuno is still basking in the glory of his first goal for the club which was set up by fellow Japanese midfielder Shunsuke Nakamura and he admits it was a proud moment for him.
"I owe great thanks to Shunsuke for the pass," added Mizuno.
"The most important thing for me was the reaction of my team-mates.
"Almost everyone came to celebrate with me - even Artur Boruc who ran from the other end of the field.
"I was very happy and it was a proud moment for me."