Alexander Povetkin has the full weight of the Russian government behind him as he prepares to fight Anthony Joshua at Wembley on Saturday evening, the promoter, Eddie Hearn, has warned.

Hearn, who believes Povetkin presents a much greater threat to Joshua’s WBA, IBF and WBO heavyweight title belts than most realise, said Russia would love to “stick one on a Brit” given the difficult diplomatic relations between the two countries since the novichok poisonings in Salisbury.

“Povetkin has got not just his team but the country and, dare I say, [Putin’s] government behind him,” said Hearn. “They are all involved. This is like a mission from them to beat Britain and for a Russian to become the world heavyweight champion.

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“He and his team know how important this is for them and for Povetkin nationally. This is not just about him personally winning a title, this is a major, major thing if he could stick one on a Brit.

“I think it adds a bit of spice, to be honest with you,” he added. “You know that level of government is involved in Povetkin so there will be plenty of instruction, well wishes and calls of intent from them saying: ‘Come on, this is important for our country.’”

However Hearn said he was “comfortable” that Povetkin, who has twice been banned after testing positive for prohibited substances, first for meldonium in May 2016 and then ostarine seven months later, would come into the ring clean. “He’s had loads of tests,” Hearn said. “Off the top of my head there have been five or six tests from the Voluntary Anti-Doping Association, not from the Russian one. They will go into his camp and that’s been done from 12 weeks out.

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“Every time there is a Vada test, one week later we get an email to both camps saying the test was done and it was negative. Once he gets into the country this week, Ukada will start as well. For me that test is not irrelevant, but is not as important as testing nine, 10, 11, 12 weeks out. Never say never, but I’m confident with what has been put in place.”

Hearn insisted that Joshua is in great shape and ready to handle whatever the Russian throws at him. “He’s got a completely different mentality for this fight,” he added. “It’s strictly business. He hasn’t really taken note of anything around him. He knows it is a really tough fight – if everyone in Britain had the knowledge of people who are involved in boxing, it would be five times bigger.”