It's all in the mind for James DeGale ahead of Badou Jack fight

The 30-year-old IBF champion hopes to win both Jack's WBC title at the Barclays Centre and to establish himself as the world's leading fighter at 168lbs.

Jack, however, has proved himself an effective fighter capable of causing upsets, as he did when winning his title from Anthony Dirrell and successfully defending it against DeGale's rival George Groves.

For all that DeGale has impressed in consistently winning on his travels he has a tendency to switch off in fights, and doing so in what is expected to be a competitive affair against 33-year-old Jack would represent a significant risk.

That streak has also posed the question whether he lacks stamina, but McDonnell is adamant DeGale's problems have not been in the body, but in the mind.

The 56-year-old is adamant DeGale considers and prepares his punch combinations in such depth he suffers a mental fatigue after several rounds. Where a lesser fighter may not plan so far ahead, DeGale's activity eventually slows him down, so McDonnell has concentrated on building his mental resilience.

"If you look at all fighters, when you're taught from an amateur, it's about your stance, your position, your jab, one-two - basics - hook, one-two-left hook, jab-hook: all basic, basic," McDonnell told Press Association Sport.

"That's all second nature. With someone like Sugar Ray Leonard, or someone like James DeGale, they're throwing sometimes 22-punch combinations, so they're whipping a shot in: double hook to the body, uppercut, treble left hook...

"He's on a three-tier thing: think, think, think. You get that 'I need to step back'.

"It wasn't his body having time off, it was his mind."

Saturday's fight is the first of DeGale's 24-bout professional career which he has prepared for with a strength and conditioning coach.

McDonnell has also tweaked his nutrition and ensured he has eaten more regularly throughout his training camp to prolong his mid-fight focus, but will regardless encourage DeGale to be more subtle if he chooses to slow down.

"As soon as you've thrown those shots, it's a 15, 20 second burst - see Leonard against (Marvin) Hagler, for example - as soon as he throws them shots, he don't keep throwing them, he goes for a walk, goes missing, on his backfoot, uses his feet and nicks a breather," he said.

"That's a perfect example.

"Speaking to people involved with other sports - not necessarily in boxing - what they do with a player when he switches off in a football match...

"A couple had different ideas - that you could do it with diet, use certain foods - certain foods feed your brain more quickly than others. I was shocked.

"One was an ex-boxer, and the other guy's involved with football. I've got another mate who's done triathlons, Iron Man. I spoke to loads of people, and when it came back, it was the answer: 'It's the brain, not the body'."