Last updated on .From the section Swimming

Burnell has not seen Tunisian swimmer Oussama Mellouli since the incident in Rio almost a year ago

World Aquatics Championships on the BBC Host: Budapest, Hungary Date: 23-30 July Coverage: Live across BBC Two, BBC Red Button, Connected TV, online and the BBC Sport mobile app. Click for full times.

You may remember Jack Burnell. Rio 2016 left him angry, very angry.

Not since London 2012, when Sir Ben Ainslie external-link famously echoed the iconic Bruce Banner warning - 'you wouldn't like me when I'm angry', had we witnessed such pure rage at the Olympics.

"It's absolutely outrageous, ridiculous, a joke," Burnell said at the time.

Like Ainslie, who felt aggrieved about other sailors "ganging up" on him, Burnell's emotional outburst was understandable.

In the swimmer's own words, and that of his coaches, he was "ideally placed" to win the gruelling 10km marathon open-water event at last year's Olympics.

But, in the closing stages, he alleges he was physically hauled back by Tunisia's defending champion Oussama Mellouli. To make matters worse, the Briton was disqualified for lashing out in response.

In a wide-ranging interview with BBC Sport, he explains how security had to escort him away from the Olympic venue before he 'found' the Tunisian, who finished 12th.

Burnell also reveals he experienced depression after the Games and details his recurring nightmares, in which he feels Mellouli's hand dragging him back under the water.

On Tuesday he will attempt to take the first step towards redemption at the World Championships in Budapest, and begin what he hopes will be a period of "sustained domination".

"It's going to be relentless," he tells BBC Sport. "Winning is the only option now at every event, and the Worlds are just the start."

'I would have liked a little word with him'

"It was very, very frustrating - a real emotional rollercoaster and I wouldn't wish these feelings or emotions on my worst enemy"

It takes a special kind of athlete to succeed in the open water - with the 10km event undoubtedly the ultimate test for Olympic swimmers.

In the pool, you have the luxury of your own lane with no athlete able to directly impact how you perform. Marathon swimming is completely different.

"You're being kicked, being scratched and being punched," says Burnell. "On top of that, there's often rubbish, dead animals and live jellyfish to contend with."

An hour and a half of fighting the conditions - and opponents - leaves athletes exhausted and emotional.

After three equally explosive interviews with the Rio 2016 host broadcaster, BBC Sport and BBC Radio 5 live, Burnell went in search of one thing - the man he believed was responsible for his result.

"I tried to find him. I would have liked a little word with him," he says with a wry smile.

"It's probably best I didn't and I did get ushered away from the race venue pretty quickly, which on reflection was a really good thing.

"If I had seen him at that point, with the emotions so high, it may have been a recipe for disaster.

"I could have torn anyone's head off that spoke to me about it. Try to picture the lowest of the low - that's where I was at."

Burnell has not seen Mellouli since, and with the Tunisian skipping post-race media interviews and stepping back from social media, he has never responded to the accusations.

'I can sometimes feel his hand on my leg'

Ferry Weertman (centre) took gold, from Spiros Gianniotis (left) and Marc-Antoine Olivier (right)

If winning Olympic gold is a "dream", then believing you're only moments from achieving that - only to be denied for reasons you believe to be beyond your control - has to be the stuff of nightmares for professional athletes.

Finishing fourth would be heartbreaking enough but Burnell has nothing to show for nearly two hours of fighting - having been disqualified metres from the finish line.

Moments earlier he had been making what seemed a perfectly timed attack for the lead before his progress was halted. Burnell responded by striking out at Mellouli to free his leg.

"Sometimes I forget and I don't think about it for a few days, but then there'll just be something that triggers the memory," says the 24-year-old.

"Then I'm feeling depressed about it and I think about how it was four years of hard work down the drain.

"I'll be laying in bed and I can sometimes feel his hand on my leg. At that point it sends shivers down my spine."

Like most elite athletes, Burnell used a sports psychologist before Rio 2016, but he has also leaned heavily on Richard Hampson since the Olympics - even though he has left the British Swimming set-up.

"Rich helped me so much, because I didn't want to pour out all of that emotion on my family as they'd been through the trauma with me out there," said Burnell.

"I felt a sense of having let them and my coaches down, because they had all invested so much in me.

"It was very, very frustrating - a real emotional rollercoaster and I wouldn't wish these feelings or emotions on my worst enemy."

'I want to prove what should have been'

Burnell does not need swimming - he is also an entrepreneur with sharp financial nous.

He tells a funny tale about how, as a child, he took advantage of Jamie Oliver's school dinners campaign, which saw the removal of fast-food from lunch menus.

The young Burnell would make money by 'investing' his school dinner money in sweets and fizzy drinks from the local supermarket, then sell them on for profit to classmates who were desperate for a sugar fix.

As an adult he has already grown and sold on a successful T-shirt printing business and has "exciting" plans for his next venture.

His immediate "unfinished business" concerns matters in the water.

"For three months after the Olympics, I didn't want to talk about swimming or think about a pool," he says.

"Even after that it was a day-by-day thing where sometimes I would think: 'Why am I bothering? What if it happens again? It's just not worth it."

Burnell made an incredible return to competition - winning the prestigious Abu Dhabi World Cup in March, beating Olympic champion Ferry Weertman in the process.

"The outpouring of public support after the Olympics was massive and that was a contributing factor to getting back in," he says.

"I want to prove to them and the world what should have been achieved at the Olympics and it would be a shame to throw away all those years of training and not give myself the opportunity."

'I have more drive than ever'

Bernie Dietzig, British Swimming's marathon lead, believes Burnell is now a very different type of athlete to that prior to the 2016 Olympics.

"We were confident that the shape and fitness he had in Rio was good enough to win," Dietzig told BBC Sport.

"With the experience he's gained, as well as the renewed focus and determination, I'm in no doubt he's in the best shape of his life."

Burnell, who swims up to 80km per week in training, agrees there has been a mentality shift.

"Before Rio I did swimming because I was good at it, but I didn't love it," he said. "Now I feel like I have more of a purpose and more drive than ever."

Sadly for swimming fans, they will be denied a Burnell-Mallouli match-up at this year's World Championships, with the latter withdrawing because of injury.

"It's a shame as I'd have like to get back in there with him, but there's no point dwelling on what happened at the Olympics," says Burnell.

"I have to move on as best I can, put that behind me and focus on winning every race up to and including the Tokyo 2020 Olympics."