Livingston striker Matthew Knox has weighed into Manchester United's interest in Celtic fullback Kieran Tierney.

United trialist Knox says fellow Scot Tierney has a big decision to make.

The Celtic star is said to be on Jose Mourinho's wish list as he freshens up his squad.

Knox told the Daily Record: "Would he be prepared to go from being a first-team player at Celtic to being a Manchester United Under-23s player with the ambition of playing in the first team? That's the question he'll have to ask himself.

"It would take a bit of convincing to get him to go and play youth football again."