Gianfranco Zola never expected to find himself back at Chelsea. Not as a club employee, at any rate, and certainly not in the dugout as assistant first-team coach given how sour his most recent taste of management proved. The Italian spent a little over four months in the Championship at Birmingham City before resigning in April 2017.

“I was very surprised when this opportunity came, considering my previous job was very painful for me,” he said, breaking away from talk of Liverpool in the League Cup third round on Wednesday night to reflect on a record of two wins in 24 games at a club in freefall. “I could not believe it. This is a blessing. A dream situation. And the best reason why I’m throwing everything I have into making the best of this experience for Maurizio Sarri and the club. Everyone knows how much I care about this club, so it’s a great opportunity.

“I’m glad for it, very grateful. But now there’s a lot of work I need to do to deserve it. I’m here totally at the disposal of Maurizio and hope I can give the best of myself for him to be successful. His success will be my pride and my happiness.”

Gianfranco Zola, seen here beating Aston Villa’s Gareth Southgate to the ball in 1999, is a legend at Chelsea. Photograph: Richard Saker/The Observer

It is more than 15 years since Zola, the player, departed Stamford Bridge just as the first rumours were circulating that a Russian oligarch might fancy buying out Ken Bates and a club whose ambitions were weighed down by an estimated £80m debt. He has returned since in opposition, as a manager with West Ham, but it says much about his glorious association with this club that he has never felt far away. Memories of so many of his 80 goals across 311 games for Chelsea, most of which he illuminated at some stage, are still so fresh. The man voted the club’s best-ever player back in 2003 is still cherished, and his appointment on the staff offered some reassurance after another summer of painful upheaval.

After all, who better to help Eden Hazard, a regular title winner but a player apparently only ever threatening to hoist himself to the level of Lionel Messi or Cristiano Ronaldo, progress yet further in his development? Or to offer Sarri guidance in this club’s particular quirks as well as the frantic and relentless nature of the English game? As it is, the 52-year-old, who has already spent time as manager at five clubs and with Italy’s junior sides, is soaking up knowledge from Sarri, the former banker.

“For me it’s a new world,” Zola said. “I thought I knew a lot about football but I was wrong. It is an amazing experience for learning. If you go back to the start of my story, I started like crazy going into my first experience in the Premier League with West Ham. It went well, but I think I missed a lot of things in my experience in management. Now I am catching up with this experience.

“I have seen very few coaches who, when they work, are so detailed or work as much as Maurizio does. What you see on the pitch is the result of the huge work he does behind the scenes. The players, most of the time when they go on to the pitch, know everything they have to do. It becomes easier for them to play. Analysis, studying the opposition, studying his own team, and then working on the pitch … I’d come across him in Italy and spoken a few times, so I knew he was good but I didn’t expect him to be this good. I hope I offer him good support. That’s why I’m here. He could do his job without me but I know the league, the players in the Premier League, I know the club. I can give my knowledge to him.”

It will be a much-changed Chelsea side who confront Liverpool in the Carabao Cup, with one eye on the Premier League meeting between the teams at Stamford Bridge on Saturday. But the philosophy, the so-called Sarri‑ball, will be the same even if the personnel have been tweaked: the onus will be on attack.

“I would have enjoyed playing in this team,” Zola said. “If you see the stats, up to now we’ve played the majority of our games in the opposition’s half with a lot of touches of the ball, especially our strikers, in the last 20 metres. A striker with my qualities would have enjoyed that very much.” Those days are gone, but Chelsea will still relish having Zola back on the books.