The Minnesota Vikings had already held their off-season programme and head coach Kevin O’Connell was back home in California.

He and the rest of the organisation were looking forward to the new NFL season when, on 6 July, O’Connell got the call that head coaches “fear more than anything”.

He was told that in the early hours of that morning Khyree Jackson, the 24-year-old cornerback Minnesota selected with their third pick of this year’s draft, had died in a car accident in Maryland.

O’Connell was “absolutely crushed”. Although Jackson had only spent a short time with the team, O’Connell saw enough to believe he was set for an “unbelievable, successful career”.

“It’s still something I think about almost every day,” he told BBC Sport.

“You learn about what type of football character and personal character players have, and I think the most special thing about Khyree Jackson was his journey was filled with peaks and valleys, some bumps in the road.

“He went to multiple colleges and really had to learn, as a young person, exactly what he was going to set his mind to. ‘Hey, I’m going to achieve this goal, I’m going to overcome this adversity, and I’m going to come out better on the other side’.

“I have no doubt Khyree would have been a major part of our organisation for a long time.”

Despite his loss, the Vikings have won their first four games of the season and in a wide-ranging interview before Sunday’s game in London, O’Connell spoke about:

The Vikings reported back for training camp on 22 July and counselling was available to everyone in the organisation.

O’Connell was among five members of the Vikings staff that attended Jackson’s funeral in Maryland, while the player’s family attended a celebration of life in Minnesota, as well as the team’s first pre-season game.

“It’s not something I had been through before, but I thought it was very important to do a couple of things,” said O’Connell, 39.

“I wanted to authentically allow our team to feel the emotions they were feeling and to work through them. I did not want to ask them to put it out of their mind.

“The other thing was leading in the face of adversity. I needed to be the rock for our organisation, to be standing out front, but also showing some vulnerabilities, personally, so that guys knew that it was OK to be grieving and that we would work through this together.”

The team has kept Jackson’s locker at the training facility as it is. They will set up his locker at Tottenham this weekend, just as they do for every game, and players and coaches will continue to wear helmet stickers and lapel pins bearing his initials.

“My job now, knowing what a special person and player he was, is to make sure we maintain our memory of him and that he remains an impactful member of our organisation,” O’Connell added.

“Most importantly, we’ll continue to make sure his family know they’re always part of our family and the special thing we have going on here.”

In seven years coaching across four teams, O’Connell formed an idea of what kind of culture he wanted to build as a head coach – one that’s player led.

Since the Vikings gave him that opportunity in February 2022, he’s challenged his players to have input and ownership, to “create something that’s one of one in being totally connected with our players”.

“I knew that if we could get that right, we would get the football right,” he added.

O’Connell says that communication, discipline and accountability are key factors to a mindset where his players “care about doing things for a reason greater than yourself”.

He also spoke to them about being “situational master” and executing when the game is on the line, and they have become used to overcoming adversity on and off the field.

Eleven of their 13 wins in 2022 were by eight points or fewer. Last season quarterback Kirk Cousins and star receiver Justin Jefferson got injured, yet they remained in play-off contention till mid-December.

“I think it’s ingrained in the team that if there’s time on the clock, we’ve still got a chance,” said O’Connell.

“We’ve combined that euphoric experience of winning all those games in 2022 with 2023, when we got a different kind of lesson. Dealing with that adversity, I think there was a lot of organisational growth in our mindset and understanding what we’re going to be about moving forward.”

Now they are one of just two NFL teams to remain unbeaten – along with last season’s Super Bowl winners the Kansas City Chiefs – and O’Connell believes Jackson’s loss has provided them with extra inspiration.

“I think so, because it’s allowed us to focus and have a reality check of nothing is given,” he said. “We understand how blessed and fortunate we are to do this on a daily basis because it can be taken away in a moment.

“So let’s make sure we maximise every moment we have with one another, understanding how special a place this is, what the players have built here.”

There was more adversity this summer as, not only did the Vikings lose Jackson, but their first draft pick suffered a season-ending knee injury in August.

JJ McCarthy was selected with a view to becoming the Vikings’ new franchise quarterback, but his injury meant that Sam Darnold began a season as the starting QB for the first time in three years.

Darnold was the third overall draft pick by the Jets in 2018 but the Vikings became his fourth NFL team this year and Sunday’s 31-29 win over the Green Bay Packers means the 27-year-old has won four straight games for the first time in his career.

“Sam’s had a really unique quarterback journey,” said O’Connell. “Not to touch on any one place, really all we focus on here is being right where our feet are planted and how we can help these players.

“I did feel like, with the environment we have, Sam could play really well here. The maturity he’s found along his journey put him in the right place at the right moment to have success this year.

“What Sam’s been able to do has not surprised me. In fact, I expected it. I think he expected it as well. Now it’s a daily process of consistency.”

Cousins had arguably the best season of his career under O’Connell in 2022. The Vikings then remained competitive despite having four starting quarterbacks last season, and now Darnold has led a winning start.

Having had a brief career as an NFL quarterback, some say O’Connell is a ‘quarterback whisperer’. He said he’s simply reflected on “what I felt like, what I wish I would’ve known going into it”.

“That’s really how everything is farmed here,” he added. “We build everything backwards from what we believe is best for a quarterback.

“I’m also the play-caller as well as head coach, so I have to build that relationship and have an understanding of how these guys tick. It’s getting them comfortable, building up their confidence, and providing them with opportunities to impact the game.

“I don’t know if that makes me a ‘quarterback whisperer’ or not, but my number one goal was to be a coach where players say ‘I was pushed and had every opportunity to be the best version of myself’.”

O’Connell tries to be “authentic” with “humility and grace”, and believes his players would say “they know they’re getting the same guy every day, that’s compassionate and cares about them, but also coaches them hard”.

Despite only playing in 10 of their 17 games last season, Jefferson still reached 1,000 receiving yards for a fourth straight season.

The 25-year-old is fourth on the all-time list for most yards in a player’s first five seasons and could become the first receiver to be named MVP since 2013.

“It’s just remarkable what he’s able to do, I do think he’s one of one,” said O’Connell. “There’s only so many people in professional sports, like Steph Curry in basketball, that you have to defend differently.

“Sometimes teams triple-team Justin but he still has an impact. There’s a maturity that comes with knowing you’ll very rarely get to just play somebody one-on-one.

“He’s got the ability to be one of the greatest receivers ever. I think what separates the really good players from the truly great, Justin has. That’s competitiveness, work ethic, he’s a great team-mate, he loves playing football, and then he’s got all the physical gifts and the intangibles that I think drive those players to reach just absolutely astounding heights. I think he’s still getting better too.”

Three days before being appointed by the Vikings, O’Connell won the Super Bowl as the Los Angeles Rams’ offensive coordinator.

The Vikings fell at the first play-off hurdle at the end of the 2022 season, and after a turbulent season last term, O’Connell is wary of saying whether his team can turn their unbeaten start into a Super Bowl run.

“I’ve learnt to worry about one game at a time,” he said. “It can be a cliche until you live a season like the last one. It’s more than something that goes on a bumper sticker or that coaches preach. It’s a reality that hits you.

“I think the key is having a short-term focus built around what we want to be as a team, both from a football philosophy and a culture standpoint. I’ve been using the term ‘progress is the process’, meaning our daily goal is to get a little bit better.”

The Vikings’ last trip to London came early in their winning run of 2022, when they beat the New Orleans Saints 28-25 in arguably the most entertaining NFL game played in London to date.

They return against a Jets side hoping to make a long-awaited Super Bowl run having built a young, dynamic roster around veteran quarterback Aaron Rodgers.

After his first season with the Jets was wiped out through injury, the four-time MVP has led the Jets to a 2-2 record so far.

“There’s nobody I respect more at that position,” said O’Connell. “He’s maybe the purest thrower of a ball we’ve had, and yet so smart because of his ability to see the whole field. You better be prepared and do your job because if you don’t, he can make you look silly in a hurry.

“I know the excitement the Jets had. It’s great to see him healthy again. Playing against Aaron is going to be a huge challenge, but you’ve got to play well in all three phases against the Jets or you won’t have a chance.”