Carlo Ancelotti says Holger Badstuber will only be allowed to leave Bayern Munich on loan.
Badstuber has been struggling to secure regular first-team football under Ancelotti - partially due to injury - and has been heavily linked with a move away from the Allianz Arena in recent weeks.
Manchester City and Hamburg have been credited with an interest in signing the 27-year-old and Ancelotti would not veto an exit this month, but only if it is on a temporary basis.
"If Holger wants to leave, we would be open to that," Ancelotti said at a news conference.
"But we are only willing to let him leave on loan, we do not want to sell him."
Badstuber's potential departure could leave Bayern short of options in defence, but Ancelotti sees no need to bring in reinforcements ahead of the second half of the season.
"The squad is complete," he added.
"We do not have any plans to sign new players in January."