The German defender talks openly about Arsenal's season-defining month, berating Mesut Özil and how the club's fans 'go mental' when his brother travels with them to away games

Per Mertesacker is lecturing and he is eminently qualified to do so. The subject matter is history and psychology, through the prism of Germany's habit of beating England in international football matches and Arsenal's big, friendly centre-half from Hannover is on a roll.

"You respect us for our footballing past but what happens when you play against us is that it's always the same," Mertesacker says. "All of our young players in Germany, they don't even know what happened previously but in England, especially the newspapers, they remind us how well we did or how frightening we are or how we always win no matter what happens and that makes us even stronger.

"We would normally have forgotten but you always remind us. I think it would be better for the English people if they think that it's now a different German generation and you just try to beat us or maybe try to copy us. You'd have better karma."

Germans, eh? Mertesacker does not even mention the Wembley friendly between the nations from last November, when he headed his country's winner – a personal high in a season of stellar levels. The 29-year-old has great expectations for the World Cup finals in the summer. But before that, Mertesacker is consumed by another well-worn narrative and it is one that he is determined to rework.

Arsenal have not won a trophy since 2005 and, although they sit two points clear at the top of the Premier League with 14 matches to play, nagging doubts remain about their durability. They have form for implosion.

"Nobody knows how to treat us at the moment," Mertesacker says, and he is probably right.

Arsenal have had their season charted by potential crash points, when the tailspin was supposed to happen and Mertesacker describes the one that is now upon them as the "proper test". They visit Liverpool on Saturday lunchtime before they play Manchester United (also a league match); Liverpool in the FA Cup and Bayern Munich in the Champions League. The games come in the space of 12 days.

"There are a lot of mental tests," Mertesacker says. "How good are we when we maybe get another setback? Are we able to come back in the way that we have always come back this season?"

Mertesacker chooses his words carefully but it is clear that he thinks there is something different about the Arsenal of this season, something hardier and capable of taking a surer route. "That's what I try to explain, although it's really hard because we haven't proved anything yet," Mertesacker says.

He talks of the depth to the squad, how he draws "strength" from the sight of players stepping in for injured team-mates to make the difference, as Alex Oxlade-Chamberlain, for example, did with his two goals against Crystal Palace last Sunday.

Above all, though, he advances the sense of precision and successful fine-tuning, from the club's record signing of Mesut Özil last September to the work of the assistant manager, Steve Bould, on the defensive drills in training. With Mertesacker's partnership alongside Laurent Koscielny to the fore, Arsenal have been miserly at the back this season.

"Steve likes to work with us, especially with the back four," Mertesacker says. "We are grateful for his influence, his tips and his little hints as to what we might do better in any situation. We've worked just on details and that's what it's about, that's what really pays off now. From the start, he tried to be an influence. He's a good addition on the coaching staff."

Özil, who Mertesacker played with at Werder Bremen, has been a mood-changer, even if he has been quiet at times. "To reach another level, you sometimes need the right addition to lift everybody, not just the players but the whole club and the whole public in between," Mertesacker says. "We didn't need five or six players late in the window, which is what Arsenal got when I arrived [in August 2011]. It is not easy to get everyone settled. We were a good squad and we didn't lose any players over the summer, which was the main part. But we needed that right addition and we can say that Özil was it."

Özil's signing followed the failed pursuit of the Liverpool striker Luis Suárez, whom Mertesacker will face at Anfield. "Suárez is like a cheeky boy, he looks like a cheeky boy who can really switch on and off how he wants to be, so that is really something," Mertesacker says. "When he is on the pitch, what is going on around him doesn't bother him.

"He is just a pure striker and that is what comes out after the transfer requests and him saying: 'It's better for me to leave because I want to play Champions League.' When we heard that Arsenal might be interested in him, obviously we were up for it and we thought, 'Yeah, he would fit in.' But after, we got Özil."

Mertesacker sports a pale yellow bruise to his left temple, the legacy of a stray elbow from the goalkeeper Wojciech Szczesny on the training ground and the buffeting, whether physical or mental, has come to feel relentless.

Mertesacker says that he misses the winter break he enjoyed in Germany at Hannover and Werder while he admits that he struggles to sleep after matches, particularly those in the evenings. "After you have won a game, you can maybe smile for a minute and then you have to think: 'How can I recover as quickly as possible,'" Mertesacker adds.

Yet there is the competitor's relish for the challenges ahead and it is plain that Arsenal has got under his skin. He feels that he owes the manager, Arsène Wenger, for helping him through an error-strewn and injury-curtailed first season and he is ready to extend his contract beyond June 2015.

"The first year wasn't that successful but, after that, with how the manager dealt with the situation and helped me to come back even stronger … that is something very special so that's why my target is to extend my contract here," Mertesacker says. "We are in good progress with the negotiations. It's up to the manager, of course, but I am really up for it."

Mertesacker ticks the boxes for fan worship, being stylish, wholehearted and, in the words of an Arsenal fans' song, a 'big, fucking German'. "It took me a long time to understand the song they sing about me, that it was not them trying to bully me," Mertesacker says. "People explained to me that it was more an expression of love."

Mertesacker is down-to-earth, as was evidenced by his decision to choose community rather than military service, after he signed his first professional contract at Hannover, and going to work for three hours each day at an institute for the mentally ill. "That kept my feet on the ground," he says.

Arsenal fans also delighted in his on-field berating of Özil following the 6-3 defeat at Manchester City last December; Özil had made straight for the dressing room, and not the travelling supporters. "We have to present ourselves as a unit, no matter what happens," says Mertesacker. "That is what Arsenal stands for.

"He was just angry, so was I and, sometimes, it's good to argue, to let your feelings out. It's nearly disappeared in football life because when something happens, players keep it inside and they are pissed over the next three weeks. That's not what I want to see with anybody. There can be a little battle but, afterwards, shake hands and forget about it. That is a culture I like."

Mertesacker's brother, Timo, has come to like the culture of English football and he likes it so much that he looks to coincide his visits from Germany with Arsenal away fixtures. He travels to them on fans' coaches.

"He loves to feel the atmosphere of the coach and the away fans," Mertesacker says. "It must be really strange for the fans as well because he looks like me. He's three years younger and three or four centimetres smaller. He might say, when he talks to the fans, 'There's my brother, he's playing today.' A few have gone mental. He just wants to improve his English, too."

Mertesacker is focused game-by-game but he cannot resist a peep at Bayern, who knocked Arsenal out of last season's Champions League en route to the trophy. Arsenal did win the second leg of the last-16 tie 2-0 in Munich but it was not enough to prevent the away-goals exit.

"Under Pep Guardiola this season, Bayern look even sharper and with more possession," Mertesacker says. "I thought that they were the best team in Europe last season and it would be really hard for them to improve but they've done it. They have the Barça style in their mind from four or five years ago, when they smashed everyone.

"But it's not a worry because we know that we can beat them. The key is the first leg at the Emirates. We had too much respect for them last time so it's up to us to create something special. Can we compete with these teams or not?"