Thomas Tuchel has challenged Chelsea to stop fixating on the scoreboard and coasting when in the lead.
The Blues rounded off their Champions League Group H campaign with a galling 3-3 draw at Zenit St Petersburg, finishing second behind Juventus.
The Stamford Bridge side had already secured their slot in the last 16, but twice squandered control in Russia - to take their goals conceded tally to six in two matches.
A frustrated Tuchel insisted his players were still taking his messages on board, but have fallen into a bad habit of relaxing once ahead in matches.
Chelsea will jump straight from Russia to hosting Leeds in the Premier League on Saturday, where Tuchel will demand standards rise quickly, especially in light of last weekend's 3-2 defeat at West Ham.
"I won't take it personally that you make a judgement here that my players are not listening to me, which I don't find so nice but I leave it with you and your opinion," said Tuchel.
"I think that we had a very good first 15 minutes and we stopped doing the things we did in the first 15 minutes.
"We were forgetting why we were the better team, because of the investment, the level of concentration, the level of physical investment was high enough to be the better team.
"Once this drops, five, 10 per cent, and it does; once we start managing results and changing our behaviour from what the score is, we get punished at the moment.
"It happened to us at West Ham and it happened again today. The reaction was good again, that shows me that it's not about what we can do, because we can do it.
"Suddenly when we concede two goals we can step up, we can show a reaction. But once we have the lead we give it away again, like also today.
"The last six minutes again we started playing balls back, we started not attacking in the same aggression, the same hunger as before and we got immediately punished, now twice."
Timo Werner bagged a brace and also teed up fit-again Romelu Lukaku for a tap-in, but the Blues leaked three frustrating goals on a chastening night on the road.
A host of enforced changes due to injuries and fatigue took their toll on Chelsea's usually-rigid tactics, but Tuchel remains unsatisfied with the current state of affairs in west London.
"My analysis is very clear: our behaviour changes when we have a lead and this is something we never did and we should never do," said Tuchel.
"We do the things that we want to do on the highest level and we push ourselves and it hurts and it has to hurt.
"You have to play through pain - physical pain - and you have to raise your level of concentration and you have to overcome adversity.
"If you change your behaviour because of the score, you allow the possibility to get punished. And it's very easy; we need a higher level of sprints, a higher level of runs, a higher level of intensity and concentration.
"It's as easy as the basics. The basics need to be pushed onto a higher level while we are in the lead."
When is the draw for the last 16?
The Champions League last-16 draw takes place in Nyon, Switzerland on Monday, December 13.
The last-16 ties will be split across different weeks, with the first legs taking place on February 15-16 and February 22-23. The second legs are then on March 8-9 and March 15-16.
What's next?
Chelsea host Leeds at Stamford Bridge in the Premier League (kick-off 3pm); Zenit visit Dynamo Moscow at 11am on Sunday.
Pimbemos
18
The Coach has said everything the team is doing. The moment they take the lead then they will start playing the balls backwards and relax and they will also stop defending. Look at the third goal they conceded, nobody was closing the player down. Caesar was watching, James was nowhere to be found etc.
raccdkmpt
15
Chelsea is just another useless team.. every season Chelsea are like this.. bring in coach first half of the season did well and when second half of the season is about to start Chelsea will Lost form again and coach will be sack.. is like a curse in the football team.. this is not normal at all.. Chelsea will start the season with a good defensive display but just wait at the end of the first half or beginning of second half Chelsea will start conceding a lot of goals as a result of poor defensive organisation. they'll start playing like cartoons, very lazy and dull ever since that has been the norm of Chelsea football club