Kieran Tierney admits he has found it hard getting back to full fitness.
The summer signing made his sixth start for the season in Wednesday's 1-1 draw with Vitoria after coming back a hip injury.
He told the club's website: "I feel comfortable. As I say at the end I was tiring, but I try and give 100 per cent. I don't save myself for maybe the last 15 minutes.
"I have given my all and if I tire, I tire. Just near the end I was just a wee bit tiring, which is understandable from the load that I have done coming back and coming into Premier League games as well. It is hard."
