Nani has been strongly linked with a move since last summer, with Juventus thought to have been closest to landing the Portugal international in January.
The former Arsenal target stayed put, although that has not ended speculation linking him with an Old Trafford departure.
And A Bola reports that Nani may still make a surprise return to Sporting Lisbon, the club he departed for Manchester in 2007.
As part of any agreement, United would reportedly seek a first right of refusal on William Carvalho, the 21-year-old Sporting midfielder who has also been linked with Arsenal.
United have already scouted him more than five times this season, and the Portugal international is highly regarded in his domestic league.
His Sporting contract does not expire until the summer of 2018, and he has a massive £37.5m release clause.
He's made 17 appearances for his club this season, scoring two goals.