"I trust him one-million per cent!" Callum Johnson believes close relationship with coach Joe Gallagher will keep him on the road to second title shot

Callum Johnson has been putting in the hours in the gym as he prepares to fight Marko Nikolic this Saturday.

But while the Boston light heavyweight has been getting his body ready, coach Joe Gallagher has been doing the homework on their Serbian opponent.

And Johnson, 36, has every confidence Gallagher will put together the perfect plan as the two meet at London's Copper Box.

"I trust him one-million per cent," Johnson said. "I trust him to watch him (Nikolic) and help me win the fight.

"If Joe's confident then I'm confident. I trust his opinion and knowledge all the way. It takes a lot of worry from me."

Johnson and Gallagher have been working together since 2010, when the Bostonian turned pro after winning gold at the Commonwealth Games in Delhi.

The past decade has brought highs for Johnson as he earned British and Commonwealth titles, but huge lows including injury, inactivity and the death of his dad Paul.

But the dark hours have only strengthened the relationship between fighter and coach.

"He was there for me in my tough times and when things were going bad," Johnson added.

"When things were being said about Joe, I stuck by him and always trusted him.

"We're on the right road, we're active and hopefully we can work our way to that world title shot again. We're just enjoying it and making the most of it as it won't be here forever."

Indeed, Johnson may feel as fit as ever, but other aspects in his life are making him more aware then ever that the clock is always ticking.

"That's sinking in now as well, it never did before," he continued.

"Before, I used to think I've got forever and now I'm realising I don't. I'm training well, my fitness and strength is as good as ever, if not better. But it won't last forever.

"I feel like a 25-year-old kid. I don't feel any different to when I was 25.

"I'm mentally stronger. But when my son hit 13, that's when things really hit home and I thought 'wow, I've got a teenage son.

"At the Commowealths he was two and I've always seen him as that little boy.

"He got to 13 and it was like a massive wake-up call. You're a man, you're nearly past it. How did this happen?

"Luckily, I've always looked after myself out the ring, never abused my body with drugs or drink. I'm healthy and fit and still got a few miles in the clock yet."

Corbon, Johnson's teenage son, has had the opportunity to watch his dad's pre-match prep during the school holidays, accompanying his old man to Gallagher's gym in Manchester and even putting in some work on the pads.

"I don't think he'll get into boxing as such, but he enjoys a knock," Johnson added.

"He likes coming to the gym as the lads are here. He's around (Anthony) Crolla and Joe and they're famous people in boxing. He gets a buzz from it.

"He can say he was with Crolla on the pads and he can get a bit of an ego from it."