Barcelona coach Ernesto Valverde has hinted they could move for a centre-half signing in January.
Valverde admits the final decision will depend on the fitness of Samuel Umtiti.
The coach said, "Reinforcements this winter? At the moment I only think about the players I have.
"If Umtiti suddenly recovers all his means, we would be extremely happy. It will be necessary to see if our prediction of having three central defenders is the right one."
Among the players being linked with Barca is Chelsea outcast Andreas Christensen.
The Dane is aware Barca have made contact with the Premier League side and is eager to hear what they have to say.