Following his knockout loss to two-time undisputed champion Oleksandr Usyk in July, Dubois has decided to part ways with Don Charles, the man behind victories against the likes of Filip Hrgovic and Anthony Joshua. 

Taking Charles' place will be Tony Sims, who is building an impressive stable. 

Here's everything you need to know about the man looking to guide Dubois to more success at heavyweight. 

Who is Tony Sims?

Tony Sims is one of Britain's most experienced boxing trainers and is based in Essex. 

Sims is very hands-on with his fighters, often getting involved in strength and conditioning and fighter management. 

A number of notable names in British boxing, past and present, have worked with Sims including Conor Benn, John Ryder, and former world champions Darren Barker and Ricky Burns. 

Has Tony Sims worked with heavyweights?

Tony Sims is no stranger to working with heavyweights and once trained British boxing superstar Anthony Joshua between 2013 and 2015. 

Recently, Johnny Fisher has joined Sims' gym after a long tenure with Mark Tibbs. 

Why has Daniel Dubois changed trainers?

After being knocked out by Oleksandr Usyk in a high-profile encounter, the fallout felt endless for Daniel Dubois. 

First, there were questions as to whether he had the right training team around him, then came the news that a party was taking place at his house on the day of the fight, which resulted in 'Dynamite' arriving late to Wembley Stadium. 

Sometimes, a change in surroundings is needed to provide a reset, and it feels like that is what Dubois has opted for as he attempts to become a two-time world champion. 

Since the news of Dubois changing trainers became public, the former world champion issued a statement explaining his decision. 

"I want to take this moment to thank Don Charles and his team for all the time, effort and hard work they've put into me over the past 18 months. I'm truly grateful for everything," Dubois wrote. 

"That said, I feel it's time for a change, a fresh approach for the next phase of my career, as I push forward to become a 2x heavyweight champion of the world, god bless.

"I'll be making a further announcement regarding my new team structure very soon." 

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