According to Di Marzio's report, the 22-year-old will undergo a medical upon arrival in Italy before finalising his season-long exit, with the clubs having agreed over a €1m loan fee.
It is also understood that the Italian outfit will be handed the option to buy the player outright for €8m at the end of the season. And it has been reported that the move is due in part to Carlos Sanchez moving to the London Stadium this summer.
Fernandez provided one assist in 16 appearances for the Hammers last season but will have an opportunity to prove his worth in another league this year. The Switzerland international has been with the club for two years, having joined from FC Sion in 2016 but isn't part of Manuel Pellegrini's plans for the campaign, especially given Jack Wilshere's arrival earlier this summer.
The former Manchester City boss is expected to oversee huge improvements this season, following their struggles under both Slaven Bilic and David Moyes in the last.
The new manager is due for a tough start to life, however, with his first match back in the Premier League set to be one away against Champions League finalists Liverpool.
They do have a seemingly easier fixture next, as Bournemouth are scheduled to visit. But their next five matches will see them pitted against Arsenal, Wolverhampton, Everton, Chelsea and Manchester United.