Adam Masina is having medical at Watford on Friday ahead of permanent transfer from Bologna, according to Sky sources.
The former Italy U21 international, who has also been of interest to Everton, has already agreed personal terms with the Hornets.
Sky Sports News reported last week that Watford had agreed a deal with the Serie A club to sign the 24-year-old left-back.
Masina has a year left on his current deal with Bologna, who finished 15th in Serie A last season.
The Morocco-born full-back made 35 appearances in all competitions last term, 34 of them in the league.
Deulofeu, who spent the second half of the 2017-18 season on loan at Vicarage Road, scored one goal in seven Premier League appearances during his temporary move.