John Terry has said he was "shocked" to be substituted at half-time in August's 3-0 defeat to Manchester City and believes that match played a significant role in Chelsea's struggles this season.
Chelsea made a poor start to the season, losing the Community Shield 1-0 to Arsenal before being held to a 2-2 draw by Swansea, but Terry believes the heavy defeat at the Etihad Stadium was the game that changed teams' perception of the Premier League champions.
In an interview with Jamie Carragher for the Daily Mail, Terry said: "We were so good last season, teams sat off, but two games into this season and we get beat [by City].
"Everyone saw that and thought, 'We can give them a run for their money here.' You get beaten again and the mentality changes. Teams come and have a go at you."
The match was also significant because Jose Mourinho opted to take his captain off at half-time, when City had been leading 1-0 through Sergio Aguero.
Terry, who had never previously been substituted by Mourinho, added: "Listen, you take it in your stride. I was more shocked than anything, but I took it and went out to watch the second half.
"I've got that mentality where you go in the next day, work your socks off and think to yourself, 'Right, I'll show you.' There is no point moaning, sulking or staying in the dressing room. That's not me. I've got to where I am in my career by fronting things up. So I did and I knew, sooner or later, he'd put me back in."
Asked whether the substitution had put doubt into his mind, the 34-year-old said: "Yeah, of course. It's a game-and-a-half into the season. Against Swansea on the opening day, I thought I played well. I had a shaky 45 minutes against Aguero, who is one of the best strikers in the world, but if you go back to the last seven or eight games I'd played against him, he hadn't got a sniff.
"Maybe I was due that, but you do lose a bit [of confidence] for sure. I think you pay more attention [to the criticism], too."
Terry said it was "lazy" for critics to have said his "legs have gone," adding: "You get to a stage and people say 'that's wrong' but they don't back it up. You've been there. You've played. You know your legs ain't gone. It takes a little bit longer to recover but when you're ready and the adrenaline pumps in, you are fine. I've never been quick."
Chelsea are still trying to recover their form and now sit 14th in the Premier League, with 15 points from their 14 games, but Terry has consistently given Mourinho his public backing.
"His stability is massive for the club going forward," Terry said. "What the club have done is set a precedent and said, 'He's the man to take us forward.' He will do. This squad of players won the league last season. There is no difference. It's a bad run of form.
"It's not different. The league table says it's different but it isn't. If you look for stuff [that is wrong] you will find it. You could sit there after a game and find a million things. I'd prefer to say 's--- result, let's just move on.' The quality is there, everything is there."
Terry, who turns 35 this month, is uncertain of his future beyond the end of the season, with Mourinho saying at his Friday news conference it was "too early" to agree a contract extension for another year.
The centre-back said he is taking his coaching badges and considering punditry but plans to wait and see how the season pans out.
Carragher said he decided to retire due to a lack of playing time, and Terry said: "That's always been my mentality. I have never known [how] players can go week after week not playing.
"This is the first time in my career where I have not been a regular in the team. I couldn't see myself doing that for a year or two years. But, at the same time, I couldn't even begin to think about being somewhere else or playing for someone else. Chelsea is my club. I've been here 20 years. I've looked into coaching. Playing-wise, [if I went] it certainly wouldn't be here."
Terry's only experience of playing for another club came during a brief loan spell with Nottingham Forest in 2000 and he said he would not consider playing for another club in England, although he would be open to a stint in Major League Soccer.
Asked if he regrets the Forest loan, given that it means he is not a one-club player, he said: "It's a funny story actually. Chelsea wanted to sell me then. They had agreed a deal with Huddersfield.
"After my loan at Forest, I was supposed to go to Huddersfield. Steve Bruce was their manager. Gianluca Vialli was manager here and he knew David Platt at Forest. But I did well in those games, I started five and came on in the other. Chelsea wanted more money then decided they didn't want to sell as I'd done well. I came back and got on the bench for the FA Cup final."
He said the only other time he had come close to a move was when Manchester City registered their interest during Mark Hughes' reign.
"They offered £29million for me in 2009 and Chelsea turned it down," he said. "I had a meeting with Roman [Abramovich] about it. I said to him, if the club accepts the offer then it tells me you don't want me. So then you haven't got a choice, you have got to go. But if they don't accept the offer, it tells me everything that I need to know.
"Chelsea refused the offer and that was it."