It's a little hard to tell from his tone of voice but the words suggest that Philipp Lahm is excited. "We go into the game with tremendous anticipation," says the Bayern Munich captain of Wednesday's Champions League meeting at Arsenal. He naturally recalls "happy memories" from their past two trips to London – a 3-1 win at the Emirates in the Champions League at the same last 16 stage exactly a year ago and the Wembley triumph against Bundesliga rivals Borussia Dortmund in May – but the real thrill comes courtesy of a relevance and sense of occasion that has been all but missing in the treble-winner's season so far.

Domestically, Bayern have just advanced to the DFB Cup semi-final with an effortless 5-0 destruction of Hamburg and are unbeaten in 21 outings in the league. The Bavarians are so far ahead of the competition (second-placed Leverkusen are 16 points adrift) that the Dortmund chief executive Hans-Joachim Watzke has bemoaned "Scottish conditions" in Germany's top flight.

Bayern's brutal dominance has certainly reached a level where it threatens to diminish their own achievements: the better they play, the easier it seems. With there being no doubt that new coach Pep Guardiola will win the championship, his first year in charge will almost exclusively be judged on Bayern's successful defence of the European Cup. The 30-year-old Lahm is far too professional to admit as much but for his side, the season starts only now in earnest, six months in. "We are really looking forward to coming back to the Champions League after the break of a couple of months," he says, "especially against top opposition like Arsenal."

Lahm has been watching Arsenal's progress in the Premier League closely, owing to the presence of Per Mertesacker, Mesut Özil and Lukas Podolski, his three Germany team-mates. And he likes what he's been seeing. "I follow Arsenal a bit more this year and they've left a good impression.

"They're fighting for the championship, that's not a coincidence: I believe they have developed as a team. They've become much stronger, the squad is more balanced. And they still play the way Arsenal always play. They want to have the ball, they like playing it short, and they have outstanding individuals."

Lahm's praise feels genuine but you sense it is partly informed by self-belief – Bayern tend to do well against teams like Arsenal. "We have always found it easier, and still do, when the opponent plays football as well, when they don't just think in defensive terms, don't just sit inside their penalty box. It's just nicer when the opponent plays football. But let's wait and see." He pauses, then smiles. "I hope they won't punish us by doing just that."

Lest we forgot, Arsène Wenger's side did nearly punish Bayern for losing focus in the second leg a year ago. They won 2-0 at the Allianz Arena: one more goal would have knocked the eventual treble winners out. "That game is a warning sign to us," Lahm says. "We had been very good in London, we thought nothing can happen to us in the return leg. All of a sudden you are 2-0 down and there are still some minutes to play. It shows that things can go really quickly in the Champions League. We will have that in the back of our minds."

That pyrrhic victory in Fröttmaning has since become part of Arsenal's mythology: Wenger and various players have credited it as the catalyst for the Gunners' first sustained title challenge in half a decade. The tie had a similar, if less pronounced, effect on Bayern, too."It gave us the confidence that we could go and beat top opposition," Lahm says, "opposition from the Premier League, away from home."

In the light of Bayern's winning streak – 31 out of 35 games in all competitions – it is easy to forget that it was widely anticipated that Guardiola would struggle to repeat the success of his predecessor Jupp Heynckes. Lack of motivation was mentioned as one possible reason. Lahm, however, says he was never worried: "This team didn't just happen to win the treble. It was a lengthy road. We lost two Champions League finals in 2010 and 2012, we were only champions once in three years. We know full where we have come from and how hard it has been to get to that point. It's not in this team's character to give all that up again, to simply throw it away. We have experienced getting rewarded for hard work and are hungry to do so again."

The manager has also helped, he adds, first by virtue of being new – "change keeps you alert, you can't rest on your laurels" – and secondly by being Guardiola: a man with an almost maniacal attention to detail. "He's football crazy, in a positive sense," Lahm says. "He's fan, expert and coach all rolled into one. He studies every opponent minutely, and he shows us solutions: where are the spaces, where are the opportunities, how should we play."

Many managers work in such a scientific fashion these days, he says, "but I doubt that many work this hard."

After an experimental, and slightly worrisome, pre-season, Guardiola has ended up honing the possession football that Louis van Gaal introduced in 2009 without ditching Heynckes's modifications, namely solid organisation and the option to be direct when necessary. The 43-year-old's biggest idea has been to make do without a big idea. Instead, there are dozens of small new ones each week. "We make adjustments and changes before and sometimes also during the games in order adapt to the opposition," Lahm says. "The manager will, for example, tell the striker to make different runs or position the central midfielders slightly differently in relation to each other. I believe we are now even more flexible, have even more control and are harder to figure out."

It is a "mentally demanding" regime, he says, and he would know. No one has been asked to adjust more. In a move that initially proved controversial but has since been thoroughly vindicated, Guardiola has shifted Lahm, the most freakishly dependable full-back of his generation, into a central role in front of the defence. "I knew I could do it but you learn new things there all the time, you need to use your head constantly. It's been a lot of fun for me."

Others have been even more enthusiastic about his transformation. "Lahm has become a football robot," said Mainz's Thomas Tuchel, widely seen as the sharpest, young, German coach. "In just a few weeks, he turns from the world's best right-back into the world's best defensive midfielder. Lahm in the centre is a horror for the opposition."

But not just there. In the 4-1 win against Mainz in October, the Munich-born graduate of Bayern's youth system played in four different positions over the course of the 90 minutes. "He simply cannot play badly," Bayern's assistant coach Hermann Gerland claimed a few years ago. Certainly Guardiola has found that his near infallibility on the ball is multiplied by its positive effect on his team-mates.

A careless performance in the 3-2 home defeat by Manchester City – Bayern had already qualified for the knockout stages – has given rise to the view in Germany that over-confidence and a lack of match sharpness against better teams might be the team's biggest problems. Can the lack of competition in the Bundesliga come back to haunt them in Europe? Lahm disagrees. "I think it's good when you lead from the front, we saw that last season [Bayern won the league 25 points ahead of Dortmund]. It gives you so much confidence."

The Bayern captain is also dismissive of suggestions that internal unrest, an almost inevitable by-product of the strong depth in the squad, could be a threat. "I don't think so. The biggest danger for us, right now, is facing Arsenal in the last 16. It's a tough draw. A lot can happen in those two games. It'll be two teams that are very good tactically and technically. I'm really looking forward to that game. I think every football fan is."