EFE Ambrose has revealed how abandoning their controversial zonal marking system at set pieces has enabled Celtic to perform better defensively this season – and helped to silence his own critics.

Ronny Deila’s side have been slated at times during the 2015/16 campaign for the goals they have conceded at corners and free-kicks – in their Champions League qualifiers and Europa League group games especially.

However, Ambrose, whose personal display at centre half against Fenerbahce last year cost his side a potential victory, believes the Scottish champions have become far more reliable at the back.

The Nigerian internationalist has ensured that Celtic have kept clean sheets in their last two games against Partick Thistle at home in the Premiership and Stranraer away in the Scottish Cup.

As he looked ahead to the league meeting with bottom-placed Dundee United at Tannadice this evening, he attributed the improvement to the switch from zonal marking to man marking at set plays which has been implemented by Deila.

“We defend as a unit now,” he said. “I think that has been helping us out. In the last year I think we have been slack at defending, at conceding goals at set pieces. I believe we have put that behind us. We have been working hard on set pieces and on cutting out defensive lapses.

“This year is better for us. We started off on a good note. I believe we will keep doing that and keep on working hard. We are just working on getting it right communication-wise and doing the basic simple thing right by picking up your man. We are focusing on our man, on going with him to the end, on not passing him over.

“I think a change of shape has really helped us. We try to improve on the tactics that we use. We try to go man to man instead of waiting for someone in the zone. We try to change a bit. That has helped us a bit at set plays.

“The manager decided in the training that is what he wants us to do now. He watched a bit of what has been going on and he tried to make it different. He came up with this and I think it has been helping us out in games.”

“I think it’s good. The most important thing is when we have given it a try it has worked out. So I think we will just keep doing it and improving on it. It has been helping us out at set plays and everybody is wanting to do it.

“Everyone is aware of what they have to do at the set plays. We have been working on it on the training pitch, on keeping an awareness of your opponent, of your man and making sure he doesn’t pass you on the pitch. You have to focus on your man. That is the most important thing.”

Ambrose’s frequent lapses in concentration at the back in the three and a half years he has played in Scotland have led, to be perfectly blunt, to him becoming a figure of fun among opposition supporters. He has been cheered by fans of rival clubs as he has taken to the field as a substitute.

Yet, the 27-year-old is adamant he has been unaffected by the personal abuse aimed in his direction and claims that, if anything, it has motivated him to eradicate the errors from his game.

Asked about the jibes he has been subjected to at matches, he said: “That is football. What happened makes you be like a man. It is not easy being out of the team. That is the time that you need your team mates to help you and indeed they were there for me. The coaches and everybody really helped me through a bad time. The good times will be there again.

“The only thing you can do is shut them (opposition fans) up and the place to do that is on the pitch. You have to make them realise it doesn’t matter what they say. It just encourages me to be better on the pitch.

“For me right now it’s about wearing a green and white shirt. The opposition supporters will never affect me. Football is like this. Fans try to get on someone’s back. They pick on someone. Unfortunately, recently they have tried to pick on me.

“But they have got the wrong guy because I am mentally strong in my head. I will not allow anyone to put me down. I always give my best. Even if it’s for one minute or two minutes I’m on the pitch and no more I always try to help my team out.

“I try not to listen. I try just to concentrate on the game. If anything it makes me more determined. It’s just a question of focus. The passion I have for the game makes me stronger and it will make me better even if people do this. I can point to the medals I have in the last four years. I have a lot.”