Manchester United are scouting Kieran Tierney of Celtic, as manager Jose Mourinho considers an approach for the defender in January.
The Daily Record (h/t Jack Otway of the Daily Express) reported a United scout was present to watch the left-back as the Scottish champions played Dundee.
Mourinho is yet to find a regular left-back within his ranks, with Antonio Valencia solidifying the right-back position as his own.
Luke Shaw's lack of fitness has seen him fail to impress Mourinho, prompting the self-proclaimed Special One to assess the transfer market.