Sodden with sweat, he moves on to bag work and shadow boxing to complete a dozen three-minute segments in the 32C heat of Joe Gallagher's Gym in Bolton.

It is energy-sapping to watch as he sits in deep contemplation on the ropes when his graft is done. It is 4pm. Five hours later he will do treadmill intervals back in his home city of Liverpool.

The 28-year-old is hard at work as he knows he is nearing the top of the mountain. Just one fight stands between him and a world title.

If he beats George Groves to take the WBA world super-middleweight title and win the World Boxing Super Series in Jeddah, Saudi Arabia, on Friday, it will be a dream fulfilled for the self-proclaimed "cheesy" little brother, who wanted to follow in the footsteps of his three elder siblings.

• Beating Smith would be 'pinnacle' - Groves

'Mum has a point but I can't turn back now'

All four Smiths became British champions. So far Paul and Stephen have been beaten at world title level, while Liam has won and lost bouts for the WBO world light-middleweight title.

The sight of his three elders boxing and being praised as youngsters drew Callum in as an eight-year-old.

He is thankful for the life it has provided but all too aware of the desperate sadness that comes with defeat. He, like many fighters, knows the changing rooms can be a place where tough men go to cry.

"I've been there for every world title fight my family have been involved in. I've been there in the changing rooms," Smith, 28, tells BBC Sport. "I've experienced the nerves - perhaps more when it's not me and when it's one of them.

"Defeat is tough. I lost in the amateurs, losing a controversial fight that stopped me going to an Olympic Games - and it's not a nice feeling. Being in the changing rooms with my brothers for fights they've lost having worked so hard, my mum has said all the highs aren't worth the one low.

"She has a point but I have come too far to turn away and give up now. I've chased a dream since I was a kid and if I didn't believe I was good enough to achieve it then I would have walked away. But I know I am good enough to beat Groves."

Defending world super-middleweight champion George Groves is unbeaten in three years

'Groves has a lot of miles on the clock'

Smith shared space in the same Great Britain amateur squad as Anthony Joshua.

The talent pool he honed his craft within was deep, so it is perhaps unsurprising he has chosen to let his boxing do the talking rather than opt to pursue trash talk as a pro.

A haul of 24 wins from 24 bouts has allowed the quiet man to just go about his business. As he works out before us, he is focused, rattling off the rounds and listening to trainer Gallagher shout his next instruction. "Shadow", comes the cry from Gallagher, prompting his fighter to oblige for three minutes, no questions asked.

Groves, who dislocated his shoulder in the final round of his last win over Chris Eubank Jr in February, will likely be exerting himself in similar fashion some 200 miles away near London.

The 30-year-old was a decorated amateur and has gone on to very publicly lose two world title shots against Carl Froch and narrowly fail in another against Badou Jack before finally achieving his dream with victory over Russia's Fedor Chudinov in May last year.

He has even beaten Smith's eldest brother Paul in 2011. Such a journey again ensures there will be no trash talk, just respect from the Liverpudlian.

"He has shown he can box, shown he has a boxing brain and also that he can dig in and fight when needs be," says Smith. "You need a little bit of everything to reach the top in this sport and he ticks a lot of those boxes.

"He has had a very good career to come back from the defeats he had. He kept going and you have to respect that. But it has come at a price. It has put a lot of miles and wear and tear on his body.

"I just believe I am the younger, fresher, better man and it's my time to take his title off him and for me to sit at the top of the pile."

'Very few get there'

Smith will boil his 6ft 3in frame down to 168lbs (12st) for fight night. Showered after his tough sparring, he calls through a food order to a local cafe with strict instruction for the inclusion of "loads of broccoli".

His trainer Gallagher will drive over to Liverpool in a few hours to observe the treadmill work. He feels it necessary as only he has observed the fighter enough through camp to know if he can work harder on the night or needs to be eased off.

Their bond is obvious - so much so that Smith says that when he walks to the ring at 21:00 BST on Friday in the obscure surroundings of Jeddah, it is the voices of his father, three brothers and Gallagher which will ensure it feels like home.

As champion, Groves - unbeaten in over three years - will follow him to the ring for lavish, strobe-light-filled ring walks that have become something of a hallmark of the World Boxing Super Series.

Both men know they can become the first winner of the Super Series at super-middleweight, with the Muhammad Ali Trophy as well as the world title Groves brings, leaving with the winner.

"It would mean everything," concludes Smith. "This sport is so tough and fighters start out with the same goal but very, very few get to achieve it.

"To become a world champion, I haven't just appeared here. It's been 20 years of work and ups and downs.

"It's been tough at times but to reach the top of the mountain would be a very proud feeling for me, my family, Joe and those who helped me get to where I am now."