Alan Pardew admits Newcastle's contract discussions with Jose Enrique have reached a stalemate.
The Magpies are keen to tie their Spanish full-back down on fresh terms, but have so far been unable to reach an agreement.
A lucrative package has been put to Enrique, but he has made it clear that he favours a move to a club that will be competing in Europe.
Pardew fears it is only a matter of time before he will be forced into a sale, with there little point in retaining the services of an unsettled player.
The same could be said for Joey Barton, who is also set to run down his contract at St James' Park, but Pardew claims it is Enrique who is most likely to be on his way out of the club.
He said: "The big difference between the two is that Joey seems pretty focused on Newcastle, whereas the noises coming out of Jose's camp are that he wants to get a new club playing Champions League football.
"Unfortunately we can't offer him that but that seems to be his focus. Hopefully that will change but we've offered him a massive contract which he does not want to sign, so it's a difficult position.
"There have been no concrete offers. But if he goes, it is going to leave a big hole in the team. It would need filling quickly."
While there seems to be little chance of Enrique committing his future to Newcastle, Pardew has refused to rule out the prospect of Barton agreeing fresh terms.
The midfielder is disappointed that the Magpies have so far refused to offer him an extension to his current deal, but that situation may change as the 2011/12 campaign unfolds.
Pardew said: "We are at a situation where we will play this season as it comes and we will all sit down at the end of the year and, who knows, we might do a deal then.
"You never know in this game. It's a strange business we are in.
"He's a good player, he's playing well for us and that's all I care about."