Marlon, 25, likes the idea of playing for Fulham and there is a feeling the deal could be done soon.
With negotiations at an advanced stage, the Brazilian centre-back was on the bench for Sassuolo’s season opener against Cagliari on Sunday.
Tomorrow will be a decisive day because Marlon’s former club Barcelona have a first refusal option.
Barca must now decide whether to match the offer or let him go to Fulham.
He was loaned to Nice in the 2017-18 season before Barca accepted a €6m bid from Sassuolo in August 2018.
Marlon has made 41 appearances for the Italian club over the past two seasons.