James DeGale admits his fear of failure has been a key factor in pushing him to his absolute limit and making him the successful boxer he is today.

The Harlesden-born fighter puts his IBF world super-middleweight title on the line when he takes on WBC champion Badou Jack at the Barclays Center in Brooklyn on January 14.

DeGale has been plotting the unification bout ever since he beat Andre Dirrell on points in May 2015 and became the first British Olympic boxing gold medallist to win a professional world title.

DeGale has since defended his IBF title on two occasions, against Lucian Bute and Rogelio Medina, and the 30-year-old says his underdog mentality and fear factor will ensure he passes his toughest test to date.

He told the Times: “The fear is there, like when I went in before against Andre Dirrell – that’s what it is.

“I could feel that fear and you saw a great performance from me, because I was scared.

“I remember Joe Calzaghe once said it’s all a front walking to the ring because you’re scared. I need that fear factor to perform at my very best.

“I have got the x-factor and then I need the fear factor on top of that.

“I was always better than him (Jack) in the amateurs but in his last couple of performances he has showed he is a proven world champion and a proven elite fighter. I thought he beat George [Groves] but it was a close fight.

“Look at his last three performances: Groves, Anthony Dirrell and Bute – good- quality opposition.

“But listen, I’ve been on a roll since fighting Brandon Gonzales and then [Marco Antonio] Periban. I dealt with them nicely, then beat Dirrell. Then I boxed Bute in my first defence and then Medina.”

DeGale continued: “I’m a worrier, just ask my mum [Diane]. Sometimes I struggle to get to sleep because there’s so much stuff going through my head.

“I just lie there thinking and I start playing mind games with myself and start thinking about life.

“Sometimes I play through fights in my head. I’d hate to think what [Floyd] Mayweather goes through.

“The pressure on Floyd and the status he has and what’s on the line for him is incredible – it’s so big.

“Can you imagine being part of that team? The pressure would be so intense.”