Jose Mourinho admitted Chelsea's performance in the first half of Saturday's 2-2 draw against Newcastle was "so poor" as the Premier League champions lost further ground in the title race.
Title holders Chelsea rallied with two late goals to salvage a point at St James' Park, with the Magpies taking a a shock 2-0 lead by the hour mark.
Ayoze Perez buried a shot on the half-volley shortly before half-time, and Georginio Wijnaldum later doubled the advantage from a header following a corner kick.
Ramires started the comeback for Chelsea with a thunderous strike from 20 yards in the 79th minute, and Willian tied it from a curling free kick three minutes from time.
Despite fighting back to earn a draw against Steve McClaren's side, Mourinho said he was shocked by the performance of his side going into his half-time team talk.
"We were so poor, so bad in the first half," he told BBC Sport. "It is possible to win the game with a good period but when you don't play for 45 minutes it's very difficult.
"I told the players at half-time that I have no time to ask them why they were so bad. I want to try to understand because I don't accept it."
Despite leaving his first substitution until the 61st minute, Mourinho said that he would have liked to have changed as many as six of his players at the interval.
"I am not a magician," he added. "I tried my best for the team. At half-time I said I was sorry I only had three subs as I wanted to change six.
"You cannot say that I react negatively, I complain, I am a critic. I laugh about it."
The result leaves Chelsea eight points behind new leaders Manchester United just seven games into the new season.
Asked if that was as badly as the Blues had played under him, Mourinho said: "Yes, for sure.
"I have played so many matches with Chelsea over seven years and we have had some bad performances. I remember one at Middlesbrough in 2005, 2006, something like that, we were losing at half-time 3-0, so we have had a few.
"But this first half, I can rate as one of those performances, yes. I put it down to awful individual performances. When you have so many bad individual performances, it's impossible for a team to be a team."
The Chelsea boss is yet to win a league game on Tyneside and had lost on his previous three visits, and that led him to question Newcastle's mentality.
He said: "I think maybe one of the reasons why Newcastle over the years doesn't get good positions is because of this mentality, it's because they choose some matches to sweat blood and in other matches, they don't.
"This is an attitude typical of a team that wins nothing. It's bad for them because if they play like this, they win many matches at home, and they don't. But this is their problem.
"The reality is that they fought hard, they gave everything, they followed a line that many pundits gave straight away - you have to fight, you have to kick, you have to tackle, you have to run, so they were exactly that, and they fought for a point, and I think they deserved a point the way they fought."
Willian's late equaliser denied Magpies head coach Steve McClaren a first league win, but he was able to take positives from a vastly-improved display in which summer signing Aleksandar Mitrovic played a significant role on his return from suspension.
McClaren said: "It's difficult to know what to think after that, and then you have got to try to come back down and put it into some kind of perspective, and that's what we must do, put it in perspective in terms of performance, in terms of reaction and in terms of what we have got.
"What you got was a collective togetherness, which we talked about a lot, and that wasn't just the players and the dressing room and the staff, that was the supporters because after this week, the supporters could have just waited and seen what was going to happen.
"But they didn't, they responded from the first whistle and that's what's unique about this football club, this set of fans, and the players responded and gave a performance which was more like what we want - attitude, character, organised, really disciplined and courage to play, and we played some good football.
"In the end, we could have won it; in the end, we could have lost it. With five or six minutes to go, the momentum had swung and to hang on in there.
"Yes, it was a good display, but that's the benchmark now, that's the standard."
Information from Press Association was used in this report.