“If you have the same problems all the time, then you have to give up. I accept everyone makes mistakes, but I ask how much do you learn from mistakes?
“If I have to have the same conversation with a player five times in five months then you give up. Those players are finished at Celtic because they can’t handle the way it is going.
“If the others are improving then one man can’t afford to stand still. That player might have been good enough at one point, but it won’t stay that way.
“Not everybody has reacted as I would have wanted to these confrontations, but I treat them with respect and I give everybody a chance.
“But sometimes you have to take decisions. This is not a kindergarten, it’s a high performance team and we have to get results, so you don’t have time to wait for everybody.
“When you have competition, you can stretch them and that’s why so many players have been in the team and then been out for a little while, but then they are back again and are improving.
“So, it goes in circles and we are slowly going upwards. Nir’s development is a good example. He has a big potential, but he’s not there yet.
“If he develops the way he has done in the last year, then in a year he will be a top international player. That’s what we want for him and he has a very good attitude.
“He wants to improve every day, he lives and dies for football and that’s always the start of it.
“Last year I didn’t understand where I could use him. He was not giving me everything, but again we had a good talk and he understood what I wanted and started to do it.
“It’s rarely down to an attitude problem. It’s down to a player’s understanding and knowledge and he did not understand what I meant by 100 per cent.
“We worked on three issues. The first was if I said sprint in training you sprint – not give 70 per cent.
“He had to be quicker on the ball and go forward as everything went sideways. His passing accuracy was 90 per cent. But 50 per cent of that was sideways.
“So, I asked him to look at Stefan Johansen and Scott Brown who had 68 per cent going forward. They only had 81 per cent accuracy, but I said to him if he could improve going forward and stay at 90 per cent he’d be world class. Now he penetrates much more.
“He was also too central and now he can see an angled pass and has started to widen the picture even more.
“The final thing was defensively he also had to win more ball. It was not enough for him just to be there – he had to win the ball, also.
“That improvement has been unbelievable. The work-rate with him as a ball winner has been incredible.”