The idea, Joachim Löw had said, was “to bid Germany farewell with a smile”. Friday’s effortless 6-1 win over Armenia in the last friendly before the World Cup finals did leave some happy faces behind in Mainz, but the national manager boarded the plane to Brazil with a fresh, deep furrow on his forehead.

On top of other worries, Löw must now make do without Marco Reus, his best attacking midfielder/false No9. The 25-year-old damaged an ankle ligament in an innocuous tackle in the centre-circle and was ruled out the next morning. “A dream has burst from one second to the next,” said the Borussia Dortmund player.

If Reus’s absence has not quite punctured Germany’s dream of a first trophy since Euro 96, it certainly added to what has been a fairly deflating buildup. The training camp in south Tyrol started with embarrassing revelations about off-pitch misdemeanours – Löw had lost his drivers’ licence for speeding, Dortmund’s Kevin Grosskreutz had been caught urinating in a Berlin hotel lobby – and was overshadowed throughout by doubts about the fitness of key players such as the goalkeeper Manuel Neuer (Bayern Munich), the striker Miroslav Klose (Lazio), the midfielders Sami Khedira (Real Madrid) and Bastian Schweinsteiger (Bayern), and the Germany captain Philipp Lahm.

The injury to Reus was the sort of accident that can happen at any moment but in the context of the past 10 days it seemed like a cruel, logical punchline.

The upshot of all this has been a very peculiar, unforgiving form of pessimism. Many Germans do not truly expect Die Nationalmannschaft to win the tournament – Löw even had to address questions about a group-stage exit and admitted that “change would be necessary” if that catastrophe came to pass – but at the same time, no one is prepared to accept that anything but a triumph in the final at the Maracanã on 13 July should be the target.

It is a difficult, almost impossible, starting position but as it turns out that is just how Lahm likes it. The 30-year-old breezily dismisses the pressure of having no room for error. “I actually really like the fact that expectations are so high,” he says. “Firstly, it’s normal: we have had two third-place finishes and we have to try to improve on that in Brazil. This team has been together for a long time, we have come very far.

“Of course they want us to win the World Cup back home. Maybe it would be easier for us if there were no expectations, if we were able to play with a sense of freedom. But that’s not our reality. I’d much rather be considered one of the favourites than one of the underdogs.”

This sentiment echoes a lifetime in the service of Bayern, the club who consider every single defeat as an embarrassing stain on their reputation. Lahm was 12 years old when he joined the Bundesliga’s record title winners and it would not be an exaggeration to say that the club’s you-have-to-win-everything attitude to the game has seeped deep into Lahm’s psyche.

It’s taken a few years before the tabloid media and the stammtisch (regulars of beer gardens and pubs) really warmed to the small, boyish, quiet full-back. They liked their leaders bigger, harder, brasher, but Champions League success with Bayern in 2013 opened the remaining detractors’ eyes to Lahm’s unassuming brilliance.

His consistency is so dependable – “he cannot play badly,” Bayern’s assistant coach and mentor Hermann Gerland has said – that serial wins tend to follow by way of natural consequence. There remains but one box to tick, one extra mile to be run. Can he do it, can his Germany do it?

“Yes, I believe so,” Lahm says without a moment’s hesitation. “I have seen how this team has worked in training, and I know that we will work hard and get things done in the next few days. There is enough time for all of us to be at our best against Portugal.”

As a veteran of the 2006 World Cup in Germany, when Bild had campaigned to relieve Jürgen Klinsmann of his command in the wake of disastrous 4-1 defeat to Italy that March, and 2010 in South Africa, when the loss of Michael Ballack to injury just before the tournament was widely interpreted as a harbinger of doom, Lahm knows that his countrymen have a tendency to overdose on angst.

The view from the dressing room is a different one. Much more optimistic. Or realistic, as he would put it. He rattles through the list of players with fitness concerns. Neuer, Schweinsteiger, Khedira: “They will all be all right,” he insists. Lahm himself has come through 45 minutes against Armenia, his first game since picking up an ankle injury in the DFB Cup final against Dortmund at the end of May, with no complaints. But he had expected that. “I wasn’t worried. When you’ve played the whole season it doesn’t take you long to get back to full fitness”.

Only the unfortunate Reus will fail to make it. “It’s a real shame for him and for us,” Lahm says. “But we are lucky to have other options in those positions.” Arsenal’s Lukas Podolski, who had become a forgotten man in the last couple of years, has reappeared just in time, looking sharp and ready to fill the void on the left.

The problems in preparation have brought with them signs of a new, attractive narrative, that of the team finding togetherness in the face of adversity. Lahm shoots down this notion. “I don’t see it that way at all. I have found a great team spirit here from the moment I joined up with the squad. The true test, in any case, will come later. We will have to see how people will react when they don’t play in the tournament”.

At Euro 2012, discontent within the ranks was one of the many reasons why Germany fell short. Under Löw’s enlightened, stylistically uncompromising guidance, the norm has been turned on its head. Efficiency in the opposition box and defensive rigidity, two basic traits that Germany could always fall back on, have become scarce commodities.

Lahm agrees that there is a need to balance creative capacity with more protection for the back four – “The mix needs to be right, we have to be a lot more careful in the way we switch from possession into defending” – but feels that the efficiency debate is in itself proof of progress.

“I remember times when we would struggle to create any chances, even against so-called minnows,” he says. “You only miss many chances when you create many chances. It’s actually a sign that things are going well.”

Talk of a lack of determination in the generation of technical players that have changed the face of German football – Özil and Götze – was also misguided, he adds. “Of course the younger players need to learn but when you don’t win as a German footballer people are always quick to doubt your determination. Me and Bastian Schweinsteiger have had to face up to that debate for ever.”

Nevertheless, a bit more of an attacking threat would not go amiss. “We might not get many chances against teams like Portugal or Ghana, who will defend quite deep. Scoring first changes everything. It makes everything easier for us. I’m sure the attackers will work on that in training.”

For all his confidence, there is one rather important detail Lahm does not yet know: his position on the pitch. Pep Guardiola has redeployed him in central midfield at Bayern; the transformation has been such an unqualified success that Löw is weighing up the idea.

Then again, he might need him more on the right side of the back four, the area that Cristiano Ronaldo will try to attack in Salvador next Monday. “You would have to ask the manager, it’s not my job to make these considerations public,” Lahm says. “But I played the last test game before the World Cup in midfield, so I’d expect to play there in the competition as well.”

Maybe Löw could switch him round, according to the specific needs of each game? “It’s possible but I have to say that it’s not easy for a player to keep changing.”

Lahm’s problem is that his performances have tended to contradict that assertion. He starred on the left in 2006, excelled on the right in 2010, and no one believes he is capable of anything less if he were to play in a central role over the next few weeks.

The decision will be fascinating, not least because moving Germany’s one undeniable world-class player over the last decade into the middle would amount to an admission of sorts: the solution to the malaise in defensive midfield has been staring Löw in the face all along, with a steely smile.