Cahill says any slip will mean the axe, no matter who you are.
Asked if this was the hardest he had ever been worked by a coach, Cahill said: "Maybe. I think with the squad being so big, you feel if you slip up once you might not get an opportunity for a while.
"It keeps you on your game, no one is complacent by any means. I that is a good thing. If you don't perform then you will be out.
"It's never easy when you have got a squad of international players. Also obviously with the manager, if you slip up, you will be out of the side. It is as simple as that.
"He has his own reasons for things and there is great competition."