Eyebrows were raised when Xhaka arrived from Premier League runners-up Arsenal at the start of last term, with Leverkusen coming off a fifth-placed finish and with rookie coach Xabi Alonso preparing for his first full season as a first-team head coach.

But a club who had never previously won the Bundesliga did so undefeated -- something no German side, not even Bayern Munich, had ever done -- adding the German Cup and losing just one of 53 matches in all competitions.

Speaking with AFP at the club's pre-season training camp in the picturesque village of Donaueschingen, where Euro 2024 winners Spain were based, Xhaka said last season was just the beginning.

"We know people are hoping to beat us, they will try and they will do everything," he said.

"But we still have the hunger to be where we were last season."

After the best 18 months of his career, the 31-year-old said criticism during his time at Arsenal spurred him on.

Xhaka joined Arsenal from Borussia Moenchengladbach in 2016.

He played 297 times for the Gunners but often came under fire from fans, sometimes for being too emotional on the pitch.

Switzerland captain since 2018, Xhaka was made Arsenal skipper a year later, but had the armband stripped from him after a month for an outburst against fans who cheered when he was subbed off.

While much of the criticism can be chalked up to frustrations from a success-starved fanbase, he said it has been instrumental in his rebirth at Leverkusen.

"I'm a fan of criticism, because criticism makes you stronger. This is what I believe," he told AFP.

"I don't drop my head, but I look at what they are criticising, and maybe I need to do something more, or change some things.

"I believe every player needs to go through criticism... You need to be strong in your head, and to believe and trust yourself that you can still do it.

"Ten years ago, I was a totally different type of player, much more emotional. Today, I'm less emotional. I believe that experience makes you (who you are)."

When Leverkusen played a pre-season friendly in north London in August, Xhaka returned as something the club treasures deeply: an 'invincible'.

Like Arsenal in their unbeaten Premier League campaign in 2003-04, Leverkusen finished the Bundesliga with 90 points last season, playing four fewer matches.

Xhaka said he "never thought about" emulating Arsenal's invincibles despite "seven beautiful years" at the club, adding: "I had the feeling or the belief that this only happens once in football.

"It was 2004 with Arsenal and then 20 years later, I'm part of it in Germany. (It) makes you feel special, makes you proud -- and of course very happy."

- 'See the music' -

Xhaka may not be Leverkusen's captain but he has quickly become their on-field leader and Alonso's voice on the field.

Leverkusen are one of five German teams in this season's Champions League.

Xhaka said he would guide the club's younger players, many of whom are yet to play in the competition.

"Maybe they're nervous. You can go to them, talk to them and explain it to them, but this feeling, you need to feel it.

"You need to see the music, the atmosphere (and) what it is in these games."

Xhaka will be 35 years old when his Leverkusen contract ends in four years.

With one eye on the future, Xhaka started his FA coaching badges while at Arsenal and is also an assistant coach at fifth-tier Union Nettetal.

"(The traineeship) helped me a lot, because a coach maybe thinks more far ahead than a player (does)."

At Leverkusen, Xhaka said "the most important thing is that the coach trusts me, believes in me and (the influence) I can have on the team during the game.

"We lose, we win together. And if I can try and help the coach on the pitch, I will do it for sure."