A small office at the back of a warehouse, tucked away down a side-street on the southern fringes of Barcelona, is not really an appropriate setting for a romantic story about football. Yet, on an otherwise anonymous evening in his rediscovered home city, Cesc Fábregas sounds smitten. He leans forward on a plastic chair and tries to capture the surprise and wonder he feels even when training for the club he loves.

"At the training ground it's unbelievable," Fábregas says, his voice tinged with awe. "This is the best group of footballers I've ever seen in my life. If you saw every training session we do you wouldn't believe it. The quality is incredible. I've never seen or experienced anything like that. Everyone is so humble and the atmosphere is the best I've ever seen."

The reverence of the former Arsenal icon is now deepened by an understanding of the graft and ambition bolted on to the usual romantic images of Barça. There are moments when he echoes the beguiling "tap, tap, tap" he hears as the ball is tattooed in mesmeric patterns of tiki-taka from one small man to another, from Messi to Xavi to Iniesta to Fábregas himself. But it's more interesting to hear him describe their unquenched desire – which was again apparent this week when, with Lionel Messi scoring five goals, Barcelona beat Bayer Leverkusen 7-1 in the Champions League.

"That's what shocks me the most," he says. "This team has won maybe 15 competitions out of 18 the last four seasons and they are still hungry for more. They want to do well and each of these players is worried when they don't play well. That hunger will help this team go on for a long time."

On Sunday, Barça are away to Racing Santander and Fábregas is speaking at an event for Puma, whose new Powercat 12 boot he will wear for the first time. Amid the corporate cheeriness, it is far more significant that Barcelona trail Real Madrid by 10 points in La Liga. The traditional celebratory eulogies for Barça need to be tempered by that stark statistic after 25 league games. It is a chasm that is unlikely to be closed.

Fábregas's personal conviction is bolstered by Barcelona's compelling yet spiky encounters with Real this season. "It's a new experience for me," he says of playing in El Clásico, "and it's quite strange that we've met Real three times already. We came out of them really well and I enjoyed it a lot. I think I played OK but hopefully in the next one [in April] I can do it even more."

Barcelona have beaten Real twice at the Bernabéu this season – winning a first-leg Copa del Rey fixture and in La Liga. They were cruising at 2-0 in the return cup tie at home, relishing a 4-1 advantage, and their fans at the Camp Nou taunted José Mourinho – who has only managed Real Madrid to one victory in 10 games against Barcelona. "Mourinho, stay!" the Barça fans chanted while flaunting a bogus advert: "Wanted: a worthy rival for a decent Clásico." Real struck back with two second-half goals from Cristiano Ronaldo and Karim Benzema.

But two wins and a draw against Real make Barça's 10-point deficit so unexpected. Fábregas, however, can be excused for delighting in his own role at the Bernabéu last December when he scored the final goal in a decisive 3-1 league victory. "It's definitely a special moment when you score at the Bernabéu. And it was especially good for me because my family and friends were there. After the game, we went straight to Japan to play the Club World Cup. It was a great night."

In the final against Santos, Barcelona dazzled with the speed and precision of their passing. "It's impossible to stop Barcelona," the Brazilian teenage sensation Neymar lamented after Santos lost 4-0. "They are the best team in the world with fantastic players."

Fábregas was the best player at Arsenal. It has taken him time, he stresses, to adjust to a new kind of disciplined position. "Barcelona have a very specific system and you have to stick to it. Everything is very studied. For my first games there was an adjustment because I was used to my role at Arsenal, where I could move wherever I felt I could make the best contribution.

"Here, it's completely different. Everyone has their own place and it's important you stick to your position. It took a while to remember stuff I'd learnt as a kid at Barcelona. But the memory is coming back and I'm improving game by game."

He endured repeated injuries throughout his last few seasons with Arsenal. The contrast at Barcelona is noticeable. "Physically I'm very strong and very fit. I feel the best I've been for three years. I don't think there's a specific reason because, here, we play so many games. It's more that my body was changing from a boy to a man much later than the others. Now, I'm feeling very good."

How would he compare training at Arsenal and Barcelona? "We train more, here, definitely. It was different at Arsenal. Sometimes after games we'd stay inside the gym but here we're always outside, with the ball, practising, working tactically. Even if we play almost every three days we hardly have a day off. We train a lot – nearly every day."

Fábregas's desire not to offend Arsenal is palpable. Barcelona might once have been infuriated that, after playing with Messi and Gerard Piqué at their academy, Fábregas was enticed to Arsenal at 16. Yet the debt he owes to Arsène Wenger and Arsenal is such that there is no pretence when Fábregas's face clouds during discussion of their turbulent season.

"It has been painful," he says, speaking before the outrageous comeback Arsenal staged against Milan at the Emirates Stadium on Tuesday night, when they almost overturned a 4-0 deficit in the Champions League. "It's been painful because I want them to do well as a club, and they're my friends and then there is the boss, who I admire so much and who I'm so grateful to. I don't want to see them losing or being sad or having bad moments. Hopefully they will finish the league well."

Did he see the season's nadir – that humiliating first leg in Milan? "I watch virtually every Arsenal game – unless we play at the same time. I've watched 90% of their games this season."

I ask the question more clearly. Has he ever seen Arsenal look as embarrassingly lost as they did against Milan? After a long pause Fábregas says: "Obviously it's not the same Milan side we played four years ago. They have much better players now. I think more credit must be given to the fact Milan played very well. It was not just that Arsenal played not so well. Milan had maybe four shots and scored four and that's too big a punishment in my opinion. Things would also have changed if, at 3-0, Robin [van Persie] scored – but it was a great save. If it was suddenly 3-1 then it's all to play for. But, with football, you never know. Anything is possible."

Fábregas's words now sound almost prophetic, considering how close Arsenal came to producing a miracle. Has he spoken to Wenger recently? "I went to the training ground a few months ago. I spoke to the boss then. I spoke to everybody and they're happy for me."

Yet Fábregas, who knows Wenger so well, must wince when seeing how much his mentor has suffered? "Whatever he suffered I suffered it as well. We feel the same and we always try our best. The boss is very strong and he believes in the club so much I am sure he will find a means to bring Arsenal back to where it belongs. I have no doubt because he's a great man. He knows when he is wrong and when he is right. He will find a way – for sure."

Fábregas looks uncomfortable when asked if Van Persie will leave if Arsenal fail to qualify for next season's Champions League. "I don't know," Fábregas says. "I don't like to talk about another person in this way because it happened to me when I was there. It was not easy."

He is happier celebrating the emotive if temporary return to Arsenal of Thierry Henry and his three goals. "I saw them all – even the Sunderland game [where Henry scored an injury-time winner in his final Premier League game]. We were playing at the same time but I saw it on replay. I saw the Leeds game live and his goal against Blackburn. Thierry will always be the best player Arsenal ever had."

After the last few seasons of speculation Fábregas must be relieved to have settled back home in Barcelona. "I don't really look it that way," he says. "I learned a lot. I still feel very proud and happy with what I achieved at Arsenal. Now, of course, it's a different story. I'm living another life and playing another kind of football. I'm very happy now."

Has he been surprised by the failure of English clubs in the Champions League? "Not really. The Champions League is always very competitive and you don't have to be the best team to win it.

"But if Chelsea don't go through [against Napoli next Wednesday] it's obviously surprising not to have any English team in the quarter-finals. In my years in England there were sometimes three English teams in the semi-finals. But clubs from Germany and Italy and Spain are improving.

"In Spain, it's tactically much stronger than the Premier League. But in England there is this passion. You are always trying to attack because the fans don't want you to keep possession for long. They want you to go forward – so that makes it interesting because you create lots of opportunities. A very different kind of football is played in Spain and England.

Each has their good points, and their not-so-good points."

Fábregas's evocative return to Barcelona is epitomised by him wearing the No4 shirt that once belonged to Pep Guardiola, his boyhood idol, who now manages the club. Yet, even here, romance gives way. Guardiola's future at Barcelona remains uncertain; but he is far from a quiet observer in training.

"He talks a lot. He's very demanding. He doesn't relax one bit. He pushes to the limit and if someone doesn't press 100% then Pep will tell him. He's always putting pressure on us to keep winning. No one can afford to relax. And, again, I am so surprised because normally when you win so much you take it a bit easier. But Pep wants to take the best out of us."

Does Messi, who made scoring a record five goals in a Champions League game look routine, still surprise him, even though Fábregas recognised his genius when they were young boys?

"Having him next to you is much, much better than having him against you," Fábregas says simply. "Messi is obviously very special. You can always learn from the best – and he is definitely the best. I'm always looking forward to playing next to him. But then I'm always looking forward to playing next to Iniesta, Xavi, Puyol, Busquets and Alves.

"All these players are magnificent footballers and working alongside them is improving my game all the time. That's why I'm enjoying it so much. I'm learning so much every day at Barcelona."