Lazio coach Davide Ballardini concedes fullback Aleksandar Kolarov could leave this month.
Kolarov is a target for Jose Mourinho at Inter Milan.
"Noting that Kolarov is a fantastic player and deserves to be in any club in the world, there are no irreplaceable players," said Ballardini.
"Is he on the market? That's not a question for me, I just give my view, but I'm not the one who makes the decisions."