Sir John Madejski is 'not very confident' Reading can keep hold of Shane Long if Celtic make a bid for the striker.
Reading's Championship play-off final defeat at the hands of Swansea City on Monday has increased speculation that Long could leave the club over the summer.
Celtic manager Neil Lennon has been watching the Republic of Ireland international of late and is tipped to make a bid.
Royals chairman Madejski has yet to receive an approach from the SPL giants, but fears the club could struggle to hang on to the 24-year-old.
"I'm aware of Celtic's interest in Shane Long," Madejski told the Reading Chronicle.
"Neil Lennon has been watching him for three games now. He's been at our past two games and there again at Wembley. We are still to hear anything official from Celtic but it's obvious they are interested.
"How confident am I we can ward off Celtic's interest? Not very. It's sad that we didn't get promoted because Shane would have liked to stay at Reading if we had reached the Premier League, but that has changed because we will be in the Championship.
"Shane is world class. What is the value I would place on him? £20m.
"Now we will just have to see what happens with him. As well as being a great player, he's a lovely lad. If Celtic are to land him, they will be privileged indeed because he's just a super player and a super individual.
"He has all the right credentials to go to the very top of the game. He's hard working and extremely cool in front of goal. I don't know if he will end up at Celtic, but what is certain is that he will not be at Reading next season."