The first whistle is yet to be blown at the 2019 Rugby World Cup, but Jonathan Joseph insists this England side have already won their first key battle – the one in their own heads.

Eddie Jones has made no secret of England’s use of team psychologists and specifically referred to his side’s mental fragility following their Calcutta Cup collapse in the Guinness Six Nations back in March.

Jones compared his side’s unstable mindset to ‘hand grenades in the back of a jeep’ ready to go off at any minute.

And as a result, England’s summer preparation has been as much about matters off the pitch as on it.

Joseph – who was a member of the 2015 squad that crashed out in the pool stages of their own tournament -  insists the scars have long since healed, and now his side are ready to let rip against Tonga in their tournament opener on Sunday.

“I thought the sessions with the psychologist were amazing. We were all in a room with different tasks to do and having honest conversations with each other. 

"I can have an honest conversation with Manu (Tuilagi) and know it is for the good of the team. The main thing for me is that every decision we make now is based upon the good of the team and (asking) does it put us a step closer to the World Cup or further away? If we are all on the same page then those difficult conversations shouldn't be an issue.

"The sessions we have had with a psychologist have been a case of making sure we are not going into the World Cup with any doubts or anything that can hold us back.

"We have squashed all that, sorted out any issues and nothing should hold us back and are ready to attack Tonga.”

2018 was a tough year for England under Jones, the all-conquering side of his first two seasons at the helm looked leggy and loose – sliding to a fifth-place finish in the Six Nations and a summer series defeat in South Africa.

But since then the tables appear to have turned, an impressive autumn series gave way to an improved 2019 Championship.

Joseph was missing for much of this revitalisation, recovering from a serious ankle injury that kept him sidelined for nine months. And the difference on his return is palpable.

"When I came back into the camp after my injuries I noticed the togetherness, which was huge for me," Joseph said.

"I hadn't been involved for about a year and came back into camp with expectation of what it had been like before and there was a completely different feel about it. 

“What we had done off the field has been massive for us, how we have come together as group, how collective we are with no cliques, no groups going off doing their own thing.

“We are a really tight bunch and we have worked really hard at that and I think that will pay massive dividends going forward.” 

The first challenge is Tonga this weekend in Sapporo – and Joseph has warned his teammates that brain rather than brawn will win the day against the Pacific Islanders who were hammered by the All Blacks just a fortnight ago.

He added: “You know what kind of players we are playing against. It is about being smart with your attack.

“When you have got the ball just holding your feet a bit more or whatever it might be.

“Manu (Tuilagi) can probably go toe to toe with them but for the rest of us it is different. We need to be more smart with our attack, maybe kick on the front foot a bit more, things like that which can give us that added advantage.”