Manchester Unitedwill scout Scotland international Kieran Tierney extensively next season before launching a bid to sign the 21-year-old defender in 2019, according to reports.
Head coach José Mourinho is known to be a long-term admirer of the Celtic left back, who can also play on the right-hand side of a back four.
United have been linked with moves for Tierney throughout the Portuguese manager's reign at Old Trafford, although the club have so far delayed talks for the defender.
But that will change next season, according to the Manchester Evening News, who claim that scouts will travel to Celtic Park throughout next season before meeting the Scottish club's valuation of the player - believed to be in excess of £25m.
It is suggested that Tierney is being lined up as a long-term replacement for Ashley Young on the left side of Manchester United's defence, with outcast defender Luke Shaw set to be given one last chance as he enters the final year of his contract.
United's extensive scouting missions won't be unfamiliar for fans to see, especially when they eye a major move like replacing one of the current senior players.
The Red Devils spent over two months watching Shakhtar Donetsk midfielder Fred before deciding to make a move this summer, and a similar approach was taken with fellow arrival Diogo Dalot from FC Porto.
Evertonhad been in talks to sign the left back as a replacement for their ageing defender Leighton Baines. However, the Toffees have since turned their nose up at the dealafter hearing of Celtic's high valuation.