Gianfranco Zola hailed the "remarkable" job done by Antonio Conte at Chelsea and believes the whole squad have embraced his methods.
The pressure mounted on Conte during the early stages of his tenure at Stamford Bridge following back-to-back defeats against Liverpool and Arsenal in September.
However, the Blues have responded in style by winning seven consecutive Premier League matches, conceding just once in that time, to storm to the top of the league.
Part of Chelsea's upturn in fortunes has been down to a tactical switch with Conte employing his favoured 3-4-3 formation.
And Zola, a legendary figure at Chelsea, is delighted to see his ex-Italy team-mate excelling at his former club.
"He's done very well, very, very good. It wasn't an easy job but so far he's doing a really remarkable job," Zola, who was speaking at the official unveiling of William Hill's Chelsea shop on Fulham Broadway, told Omnisport.
"He works very hard and it's good to see somebody working hard doing very well.
"I was watching the game against Arsenal and towards the end he went to a 3-5-2 system and they looked more balanced. So when he changed it I believe it was the right thing to do.
"It's the perfect shape for the team. In a way I'm not surprised and to be honest he's put a lot of work in it for it to be successful."
Chelsea were champions in the 2014-15 campaign, but endured a dismal title defence last season that cost Jose Mourinho his job last December.
Several of Chelsea's star players have looked revitalised under Conte, though, including talisman Eden Hazard.
Zola added: "I cannot make any comparison to Jose Mourinho but I know that Conte works with them physically and tactically and it seems to me that the players are responding.
"Eden Hazard is an example. I'm glad because it means that when you work it means that results are coming your way."
Chelsea's improved form faces a stiff test this weekend when they travel to the Etihad Stadium to face Pep Guardiola's Manchester City.
And Zola is expecting an entertaining contest.
"The performance of the team will determine the result," he said.
"These days nobody gives anything away they are just prepared. If you want to win any game you will have to play at your best.
"I'm expecting both teams to go and make the game. Both teams will want to enjoy the play. So it will be a good game and I'm looking forward to it."
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