MANCHESTER UNITED are reportedly set to step up their pursuit of Celtic left-back Kieran Tierney.
Jose Mourinho has been scouting the Scotland international and is poised for a £15million raid.
Luke Shaw is back training with the Old Trafford club as he bids to get himself fit in time for the start of the season.
But Mourinho questioned the former Southampton ace last season and wants another left-back.
Tierney, 20, has enjoyed a stunning rise in the last couple of seasons, winning PFA Scotland Young Player of the Season award last year and making his Scotland debut last March.
This year he was been one of the first names on Brendan Rodgers’ team-sheet when fit, getting a starting berth ahead of cult hero Emilio Izaguirre.
According to the Mirror, Arsenal have also been looked at the player, who recently played down reports of a move away.
England left-back Shaw, 21, started last season as first-choice at Old Trafford – but has since been publicly criticised several times by Mourinho.
Mourinho said that Shaw was “a long way behind” other full-backs at the club.
The Portuguese said: “I cannot compare the way he trains, the way he way he commits, the focus, the ambition.
“I cannot compare. He is a long way behind.”
The England defender has also been criticised for ‘overplaying’ injuries.
He played just 70 minutes of Premier League football since losing his place at the end of October, with only a couple of other Cup appearances.
Scouts have been sent to watch Tierney, who won the last four caps for Scotland in the 2-2 draw with England.
His performance in the 3-3 Champions League draw with Manchester City is what first caught the eye of Mourinho.