The Portuguese winger was heavily linked with a move away from Old Trafford last month, with rumours suggesting that David Moyes has deemed him to be surplus to requirements.
A loan switch to Fulham, Tottenham or a host or Italian sides was mooted as last week’s deadline drew close, but no deal was agreed.
However, Juve are ready to launch a swoop once the new transfer window opens.
The Old Lady were one of the clubs linked with Nani in January, with manager Antonio Conte thought to be a fan of the inconsistent wide-man.
He is confident that he can persuade Moyes to sell later this year, and also that the player himself will be open to the move.
Recent reports have suggested that a number of players within the United squad are frustrated with life at the club, with speculation suggesting that the ex-Sporting Lisbon man is one on that list.
The Red Devils are expected to go on a summer spending spree, which will be part funded by the sales of unused stars.