Simon Kjaer's move to Roma risks collapsing at the last minute, as Wolfsburg appeared to change the contract details.
The Danish international defender is already in the Capital and underwent his medical on Friday after the clubs agreed a fee.
Roma were set to pay €2m to have Kjaer on loan and had an option to buy at the end of the season for €8m.
However, it is reported Wolfsburg sent over the contracts to be signed with a different clause, one with a mandatory €8m signing fee rather than simply an option.
It is not yet clear if this was an oversight or a misunderstanding, but media sources claim it could scupper the whole deal.
There are only four days left to complete the transfer before the deadline.