Napoli are continuing to push Manchester United for Marouane Fellaini, but cannot decide on the transfer formula.
The Partenopei have not disguised their interest in the Belgium international midfielder, as director Riccardo Bigon reportedly visited his entourage in Brussels this week.
According to the Corriere dello Sport, there is a deadlock between the clubs on how best to proceed.
Manchester United want to make up for the £27.5m (€32.5m) fee they paid Everton only a year ago.
Napoli are adamant they will only take the 26-year-old on a paid loan with a mandatory option to buy at the end of the season.
In essence, the only real difference is that Napoli would pay over a number of years.