Colin Farrell admits he initially ''miscalculated'' his 'Killing of a Sacred Deer' co-star Barry Keoghan.

The 42-year-old actor has conceded he made the mistake of judging the 25-year-old star - whose mother died of a drug overdose - based on his youthful appearance, saying he's ''older, wiser, more experienced'' than he assumed.

Colin shared: ''My first impression of him was that he was a pure burst of Irish energy.

''He seemed young - but that was a miscalculation on my part. Before too long I got to know a little more about him and rather than younger than his years, he's older, wiser, more experienced than them.

''He's stepped between the pillars of tragic loss way more often than most twice his age and he's done so with his head unbowed.''

Colin is hugely impressed with how Barry - who is, perhaps, best-known for his role in 'Dunkirk' - has dealt with tragedy in his life.

He told the Guardian newspaper: ''I love Barry. I think all the experiences he's had in life would bury most of us.

''Certainly, I believe such struggle would place me in anger and destructiveness that is counter to what I've seen in him. He's about creating.

''Just look up his CV and see who he's worked with already, and the depth and mystery he's brought to each role. He's focused, driven and grateful, all alongside the natural talent he has.''