10 Hardest Men Who Ever Played For Celtic

If you've ever watched Roy Keane sitting beside Adrian Chiles on ITV then you'll know that the former Manchester United captain is an impatient man at the best of times. And if you've ever watched him play then you'll know that, on the pitch, he had more than just words to back up his piercing stare.

The Irishman was only at Celtic for about a minute - not enough time to seriously maim any of his SPL opponents, at any rate - but there's no shortage of footage from his Old Trafford days to evidence why he garnered a reputation for being one of football's hard men long before.

His knee-height, studs-up challenge on Man City's Alf-Inge Haland, allegedly an act of vengeance after the Norwegian accused him of play-acting three years prior, is perhaps the most notable example*.

*And one of few football clips that carries a viewer discretion warning.