Chelsea goalkeeper Petr Cech insists the midweek departure of assistant coach Ray Wilkins had no bearing on their shock 3-0 home defeat to Sunderland.
Goals from Nedum Onuoha, Asamoah Gyan and Danny Welbeck earned Sunderland their first away win of the season and sent Chelsea tumbling to their first home defeat since last March.
Sunderland outplayed the league leaders throughout and Chelsea coach Carlo Ancelotti labelled their poor performance as the worst since he took charge last year.
Chelsea were without captain John Terry with a back injury and Alex (knee) and their replacements Paulo Ferreira and Branislav Ivanovic could not cope with Welbeck and Gyan.
Wilkins was told last week by chief executive Ron Gourlay that his contract would not be renewed but Cech claimed the defeat had nothing to do with his shock departure.
"There are things that happen in football everyday," said Cech. "Managers come and go and first-team coaches and players can leave suddenly.
"So we are all used to things like that. But it's not an excuse. It was just that our performance wasn't up to standard. We didn't play well as a team.
"We gave them too much space. We were not good enough in attacking play, we were not good enough at defending as a team - not just individuals.
"We changed the back four but it is everyone's mistake. We were not compact enough. We were all over the place and that's why they had those chances and took them.
"We tried to do our usual job at home - but it wasn't to be and they profited from how we didn't play.
"We gave them a lot of space and they used that well to create good chances, attacking play and in the end they got the goals."
Chelsea failed to test Sunderland goalkeeper Craig Gordon while Steve Bruce's side looked capable of scoring with every attack.
Terry's injury has kept him out of the England squad for the friendly with France, but the captain insists the squad must move on from the departure of Wilkins.
"Ray has left the club and everyone is sad to see him go," said Terry. "It was an unexpected decision but we have to move on and stay calm.
"Ray's been brilliant since he came in, from day one, not only as a coach but as a man as well.
"Ray was a great person to have around the football club, he would pick you up when you were down and, if there was a problem for any players or staff, he would be the first one to call them to make sure everything was okay and to ask if there was any way he could help.
"All that came alongside his knowledge and coaching ability on the football field."
Meanwhile Sunderland striker Asamoah Gyan believes "everything is possible" after their shock victory at Stamford Bridge.
The 24-year-old netted his fourth goal in three games, taking his total tally to six in just four starts.
Gyan believes Sunderland have demonstrated immense potential this season and confidence is flowing throughout the squad.
"Everything is working out well," said Gyan. "I thank God for that because I am a good Christian.
"All the players did well. We have a good team with good players. We must believe in ourselves because with the kind of players we have, we should have confidence in ourselves that we can go places.
"We have proved that everything is possible. We worked hard and every time we got the ball, we played. We were not scared."