Brendan Rodgers confirmed Celtic have received an offer from Chelsea for Craig Gordon but remains adamant that his keeper is not for sale.
The Stamford Bridge club are looking to line up a replacement should Asmir Begovic, No. 2 to Thibaut Courtois, move to Bournemouth.
Chelsea reportedly bid around £3 million for the 34-year-old Scotland keeper, but speaking at Celtic's Lennoxtown training complex, Rodgers said: "There has been an offer but nothing that we would [make us] even think about moving him.
"He is a player very much part of what we want to do. He has 18 months left on his contract and I want to keep him here to build a team around. We have no interest in selling him.
"When the club spoke to me about it, my message was very simple. He is not a player we want to sell."
Asked if £3m was a derisory figure for Gordon -- Bournemouth have reportedly offered £10m for Begovic -- the Northern Irishman, who worked at Chelsea's youth academy, said: "It is certainly not his valuation, that is for sure.
"I don't want to put any numbers on it. The message is pretty clear. He is not for sale.
"I repeat again, if a player is to go out of Celtic then the club will get their worth for the player.
"It will be at our valuation, irrespective of what the perception is of the league. In the real world, every player has a valuation, but there are four days to go in the window.
"I don't want to be in the mindset of moving a goalkeeper with four days to go, a goalkeeper we have been building up to become a Champions League goalkeeper.
"To move him on and try to find a replacement is a very difficult thing to do.
"I would hope the only thing that comes out of it that we can renegotiate with Craig and get him here for a longer period than the 18 months he has left.
"Craig will tell you that even before this speculation arose, I had spoke with him and it was something I was very keen to do.
"With the interest, of course, it is maybe something that brings that forward that little bit quicker."
Rodgers believes that the former Sunderland keeper will remember that Celtic helped resurrect his career in 2014, when then-manager Ronny Deila signed him after he had been out for two years due to a knee injury.
The former Swansea City and Liverpool boss also made favourable comparisons between Gordon and former Netherlands keeper Edwin van der Sar.
He said: "Craig is a clever man. He has had a taste of the Premier League when he went to Sunderland and it didn't quite work out for him.
"I know with the type of guy Craig is, he will be looking at Celtic as the club who brought him back in to resurrect that career that looked like it was disappearing.
"And I know how much he loves being here. I believe at 34, he can go for another four or five years. He could go on playing until he is 40.
"Having had that trauma of not playing for a few years and wondering if he was going to play, the last thing you need is to go and sit as a No. 2 somewhere for two or three years and be lucky if you can accumulate 10 games.
"He has the chance here to continue enjoying what he has been doing here, playing the game at a high level, hopefully winning trophies and hopefully playing Champions League football.
"He has regained his position with Scotland after I think seven years out so everything points to his career on the up at 34.
"I think I mentioned Edwin van der Sar. He had the best spell of his career between 35 and 40 when he moved to Manchester United.
"That is in line what Craig could do with Celtic. He could go down in history as one of the great goalkeepers we have had here."