Arsenal shock helped Antonio Conte understand his Chelsea squad
Chelsea head coach Antonio Conte picked out last season's defeat at Arsenal as a turning point ahead of Sunday's clash between the London rivals.
The Blues lost 3-0 at the Emirates Stadium in September 2016, prompting speculation Conte could be sacked just a few months into his reign.
But the Italian stayed strong in his convictions and switched to a 3-4-3 formation which prompted a 13-game winning run in the Premier League title success.
"It was a really bad game for us," Conte said.
"Then we changed our system because after that game I understood very well our team. We hadn't balance.
"In that game they dominated us from the start until the end.
"After that game we changed a lot of things and then we won the league.
"Honestly, I wasn't worried (about being sacked). No, because I trust in my work. I trust myself and my idea, in my methods.
"Our job is difficult. Every day you have to think, you have to work very hard to try to have a good result.
"When the result is not good, anything can happen. We must be prepared for this.
"It can happen that one experience can be positive or negative. But for sure I don't change my mentality, I don't change my method, I don't change my idea of football."
Arsenal won the most recent meetings with Chelsea, claiming the FA Cup in May and the Community Shield, on penalties, in August.
But little more than 12 months on from Conte's first London derby with Arsenal, Arsene Wenger's men visit Stamford Bridge without a win at Chelsea's home in almost six years. The Blues won February's league game with ease.
Even N'Golo Kante struggled against Arsenal at the Emirates Stadium last September, trailing in the wake of Mesut Ozil as the Germany scored the Gunners' third.
Kante was a key figure in Chelsea's title triumph, winning the Premier League for a second straight season after his victory with Leicester.
Kante received accolades aplenty for his role in Chelsea's triumph, while Conte continually said the France midfielder could improve with the ball.
Now Conte says the 26-year-old is a "complete player".
"Last season I said during many press conferences about N'Golo that he could improve a lot with the ball," Conte added.
"He's working very hard to improve this weakness. But I think now he's a complete player - he's a top player with the ball, without the ball.
"He always knows when he has the ball what he has to do."
Kante will be an example for Tiemoue Bakayoko, his compatriot who has impressed since his summer arrival from Monaco, Conte says.
The Blues boss added: "Baka without the ball is a really strong player, a physical player.
"He can improve a lot with the ball. We are working a lot on this aspect with him."
Given his position, Bakayoko needs time to adjust to Chelsea's tactics, but Conte is happy with the man who appears to be the Blues' direct replacement for Nemanja Matic, now at Manchester United.
"We try to play with an identity and if you want to give an identity to your team, every single player needs to know very well your idea of football," Conte added.
"To have in your team a powerful player is very important, above all in this league."