David Luiz has heard the grumblings: The Fifa Club World Cup is little more than a contrived mid-season distraction, a long-haul trek to the other side of the globe for a jamboree few care one jot about. Energy will be further sapped ahead of a busy festive fixture list while rivals steal a march in the Premier League, a more accurate gauge of Chelsea's qualities, back home. The arguments are familiar, their validity persuasive in part, and yet the Brazilian rejects them out of hand. Cue the case for the defence.

For David Luiz this is actually "a dream", a trophy he has craved since his days in the youth team at São Paulo or attracting the Benfica scouts with Vitória in the Brazilian championship's third tier. And aside from fulfilling personal ambition is the pick-me-up it can offer the team. "This competition comes at a great moment for us," he says. "As a club we need to win trophies every year, so to go out of the Champions League in the group was so disappointing. If you aren't down then you don't deserve to wear the shirt. But this gives us a chance to change that feeling, a chance to be happy again. Win this and confidence will come, we will push forward. Things will feel better."

David Luiz does not do negativity. This is a player who presumably wakes up every morning confident today will be the day he will tame that trademark tangle of a mane of his, or that Gary Neville will publicly praise his defensive capabilities to the hilt. The past few months have admittedly tested that glowing optimism, with the 25-year-old now playing for his fourth Chelsea manager in a little under two years at the club, and with the exit from Europe's elite competition part of a slump that cast them to the fringes of the domestic title race. The involvement in Japan is reward for last year's exploits, but those heady memories of Munich feel increasingly distant.

Yet Chelsea arrived in Yokohama on Sunday a team on the turn. Confidence was helped by the thumping of Nordsjaelland in their final fruitless Champions League fixture and maintained by Saturday's welcome win at Sunderland. That was their first league success since mid-October, since when seven matches had spluttered by, more recently accompanied by open revolt in the stands at Rafael Benítez's appointment as interim first-team manager. Frank Lampard and John Terry missed all but 35 minutes of that run, the experienced pair leaving a void some seemed reluctant to plug. David Luiz, characteristically, thrust himself into the breach.

"When you have bad moments like that at a big club, you need to be strong," he says. "I know my personality is to be a natural leader: I was captain at Benfica at 21, I've captained my country, so I knew that, with the team's leaders of many, many years out of the side, I needed to take responsibility and try and help the young players. Players like [Eden] Hazard, a great talent and an amazing player, but someone who needs support. He's only just arrived in the Premier League, like Oscar and some of the others. Or players like Ramires, who are more shy. I need to help them.

"I've always said my shoulders are broad and I can take on that extra responsibility. I love it. I want it. I prefer to take it on myself to help the other guys, who can then go out and play with their heads clear and calm. I know what it's taken to get me here at Chelsea. This was just another moment to be strong. One day, when I have my own kids, I'll tell them that, even when their life is not easy, they can still do anything they want. That is the way to approach things."

That strength has manifested itself in everything from the thumped penalty kick against the Danes last Wednesday, moments after Hazard and the visitors' Nicolai Stokholm had missed – "Some other players might have had 'fail' in their heads by then" – to a nodded concession to discipline under Benítez. Over-exuberance can still prompt David Luiz to tear up-field, creating the impression he is living on the edge with focus drawn to his every touch, not least by that mop of hair, but the instances feel rarer. His physical strength was missed at West Ham when Chelsea ended overwhelmed. The stand-in manager has recognised class, just as Carlo Ancelotti, André Villas-Boas and Roberto Di Matteo did before him. The Spaniard may just be the man to coax the best from the centre-half.

David Luiz knows he still has plenty to prove in England. All the criticism provoked by poor positioning or his gallivanting into enemy territory – a wanderlust that prompted Neville's "kid with a PlayStation" comment – has stung him. Sometimes there is no hiding. "It does get to you. You ask yourself: 'Why are they saying this? Why can't they see I'm trying my best?' You have moments where you're down but I can be sad for one or two hours, no more. The rest of the time I have to be happy because the team needs me to be positive. My brain needs it. I need it. I know you can change any difficulties in your life and move on.

"Back when people were criticising me a few months ago I was working hard and I knew that, when I laid my head down on my pillow at night, I'm an honest guy trying my best. If the rewards don't come now, they will in the future. And in the last few games I've played really well, at the top level. If I was playing for a club in mid-table, I could make three or four mistakes and no one would notice because the analysis is not at the top level. But when you play for a big club, every little mistake is highlighted. So every day, you work, work, work. That is the key. If you don't, other guys work more than you do and, eventually, they kill you."

All that effort yielded a European Cup back in May, and could be capped by a world crown this weekend. David Luiz is one of a quartet of Brazilians in Chelsea's squad and each considers Fifa's showpiece tournament as the pinnacle. Maligned at times in Europe, the Club World Cup has come to represent a show-stopper in South America. The centre-half, a boyhood Corinthians fan born in Diadema, São Paulo state, knows his compatriots will consider Chelsea a notable scalp as they seek to wrest this trophy from European hands for the first time since 2006. "They've been talking about this competition for six months," he adds. "Corinthians will have 20,000 supporters coming to Japan, and it's a dream for so many clubs in Brazil to win this trophy. It's the last game of their season, like the Champions League final was for Chelsea, and they'll see it as an early Christmas present.

"I dreamed about winning it, too, when I was young. It's an opportunity for the South American teams to prove they can compete with the best in Europe. They can't be underestimated. The league in Brazil is similar to the Premier League now, and there's strength in depth there with 10 or 11 teams capable of winning it. Brazilian football has developed tactically and learned from Europe, and you get teams like Corinthians who are disciplined and play as a unit, with two lines of four: the game is quicker, harder.

"I know Corinthians' players: Douglas, the No10, has so much quality in his left foot; Paulinho plays in the national team; I played with Fábio Santos when I was younger, and Cassio in the Brazil Under-20s, and with Wallace their centre-half when we were 14. They are my friends. If someone had told us back then, 11 years ago, we'd be playing against each other in this competition I'd have laughed. But in Brazil, if you're born a man, you dream about playing football. And I dreamed a lot: about playing for a big club, about playing for Brazil, or in a World Cup … I've been a lucky guy." Chelsea will hope good fortune, and all that positivity, rubs off over the days ahead.