Manchester United are watching Celtic fullback Kieran Tierney.

The Daily Record says United boss Jose Mourinho has already targeted Celtic star Tierney as the man he wants to fill the left-back spot.

It is said the 55-year-old has been hugely impressed with Tierney's performance for Celtic.

And his versatility to play across the defence has reportedly made him a top priority for Mourinho.

The 20-year-old only recently signed a new six-year deal with the Scottish champions but the report states Celtic would listen to offers of around £20million.