There are reports Milan baulked at Martin Caceres wage demands after he passed a medical, so the move could be off.
The Uruguay international is a free agent and has been ever since his contract with Juventus expired in July 2016.
He was flown in to undergo a thorough medical after injuries to Mattia De Sciglio, Davide Calabria and Luca Antonelli.
Caceres passed, but according to Calciomercato.it and Gazzamercato, talks are on the verge of breaking down over wage demands.
The player wants €1.5m for six months, while Milan are offering at most €700,000 – including bonuses based on the number of games he is able to play.
It would be the second move to collapse due to the salary issue, as Caceres had previously been close to Crystal Palace.