Neil Lennon has revealed that a fear of failure drives him on as Celtic manager.

The Northern Irishman put pen to paper on a new one-year rolling contract yesterday - with no pay rise in it - and insisted that he is every bit as focused on delivering success to the Hoops as he was the day he got the job just over three years ago.

Lennon, who has been outspoken about his issues with depression in the past, admits that he finds it difficult to savour the highs that come with his post, meaning that even huge nights, like last season when Celtic beat Barcelona, are not enjoyed the way they might be by others.

His fascination with those who have achieved great things in the game, like Sir Alex Ferguson and his own mentor Martin O'Neill, revolve around how they coped with the crippling lows that can affect managers.

"You are always one game away from a crisis and that is very, very true as I have witnessed these last few days," said Lennon.

"It keeps you thinking. It gives you some sleepless nights sometimes. The one thing I fear in this job is the sack and that is what drives me and motivates me more than anything.

"Obviously producing a good team and good players and winning silverware is added to that, but the fear of the sack is the thing that motivates me more than anything else.

"Once we beat Barcelona, the one thing you think about is: we've got to qualify now. I am looking back on it and I think maybe I should have made more of it at the time but that just isn't the way I am built.

"There is no doubt the lows outweigh the highs in the job, for me anyway. Some managers might be really different and really enjoy the moments. I do enjoy the moments when they come, but I try to keep a lid on it.

"Fear of failure is a horrible thing, it really is. The fear of not qualifying for the Champions League has given me a lot of thought since April."

While Lennon agonises over coming up short, his record at Celtic makes for impressive reading.

He admits that he has taken some satisfaction from his achievements to date with the club, although it is not something that has come to him easily.

Having won titles and cups and put the club on the map in terms of their European involvement, Lennon is entitled to celebrate his own contribution to the club.

But he is always looking at what the next challenge will be - and right now that means his thoughts rarely stray from Wednesday night's massive meeting against Shakhter Karagandy.

"I think I have delivered. I have delivered players, silverware, Champions League football and I want to do it again. It is a real ambition of mine to manage at the top level with whatever club I am at," he said.

"It means a bit more to me here because I have been a player here and I do enjoy the club. But there are times when it is difficult. I have a lot of work to do here and it is a challenge.

"You look at Walter Smith and I am sure he had lows as well as highs in his career, the same for Martin O'Neill and Gordon Strachan as well.

"How do you deal with it? And Sir Alex, too. That's what fascinates me about them - how they dealt with the huge lows that they would have experienced.

"Do they get any easier? I don't know."