A silence descends on the Kickstop gym, save for the swishing followed by the clack-clack of skipping ropes.

A row of boxers try to concentrate on their work but they're all facing the ring that takes up a quarter of the floor space.

Their eyes are on two of British boxing's top heavyweights, Sam Sexton and Dereck Chisora, who are preparing to slug it out, again. Twice they have met for real, twice Chisora has won, leaving an indelible mark on the Sexton record, which reads 13-2.

One defeat in boxing is equivalent to a step back and Sexton is now looking to take two steps forward, the first of which comes on May 21 at London's O2 Arena.

Just what a victory in the ring can lead to is illustrated by the affable Londoner's recent plans: twice Chisora has been lined up to fight Vladimir Klitschklo – and twice been disappointed by the Russian pulling the plug because of injury. Now he's hoping to silence Tyson Fury.

Two big rivals who have become friends outside the ring are now helping each other's ambitions as sparring partners – until the time comes to meet again, a bout which seems almost inevitable.

If it's surprising for the casual observer to see them sparring together, it's not for the men in the middle.

'After a fight you are friends,' said Sexton, whose next opponent has yet to be named. 'It's a business. Dereck and me I'd like to say are friends and I help him out and he helps me out, that's the way it is.

'It's good for both of us – he is massive at the moment; he has to be pushing 20 stone. He is big and muscley and it is good to have someone big in there to push around and get stuck in with.'

Sexton is rated number three among British heavyweights so knows the plan is fairly simple: win his comeback fight and then get a title shot.

'If I had beaten Dereck last year it would have been me probably up against Vladimir, it would have been my fight, but then again would he have pulled out twice like he did against Dereck?' said Sexton, 26. 'You have to feel for Dereck – he has had two long training camps, probably spent a lot of money on them and the fights never came off.

'It is not going to be long for me – I am still rated number three so no matter what happens I will always be in the line. It's a long time out, eight or nine months, so it's case of getting in there, shaking a bit of ring rust out and if it is a tough fight it is a tough fight, which is good, because I will have the experience of getting in there again and hopefully just knocking on the door for titles again.'

Chisora holds the British title and the Commonwealth belt, which he took off Sexton last September – but he's predicting the British belt will be making its way to Norfolk soon.

'Sam is one of those guys in boxing you fight and then get along with,' said the 27-year-old. 'He comes from the same sort of background as the one I am coming from and he is trying to get what I am trying to get as well.

'He has a fight and I am here to help him – maybe in the future if the money is right we can get in the ring again. It is hard to win against me because I am driven so hard. I do most things that people don't do. When I can't sleep I wake up and run, if I can't do anything I call everybody and go into the gym at four in the morning training until I get tired and can go to sleep. I train any time.

'Sam will be a British champion soon because in the pipeline I might be vacating the British titles.'

The disappointments of the Klitschko postponements have long gone. 'A true champion keeps going, they can never kill your dreams,' said Chisora. 'Either way I am going to become a world heavyweight champion. We took the opportunity and God decided, 'it is not your time'. So we said, 'fine, just give us another task to do' and we have got another task and right now we have Tyson Fury.

'We just hope they come up with a date. I haven't spoken to him to be honest – but he has lost his confidence, his 'mojo' has gone. It's gone away for a while – it's a shame for him to get in the ring with me right now, but the money is right so let's do it.'

• Tickets for Sexton's May 21 fight are available by calling 07796 206124.