Arsene Wenger described his 1,000th match as Arsenal manager as a career low after Chelsea inflicted an embarrassing 6-0 defeat at Stamford Bridge.
Wenger was last month called "a specialist in failure" by Jose Mourinho and remains without a victory in 11 attempts against his nemesis after a spectacular implosion and an horrendous error by referee Andre Marriner, who mistakenly sent off Kieran Gibbs.
Wenger did not attend his press conference, but told the BBC: "This defeat is my fault, I take full responsibility for it.
"I don't think there's too much need to talk about the mistakes we made. We got a good hiding today.
"It's one of the worst days (in my career). It's over after 20 minutes and it's a long game after that. You don't prepare all week to experience that kind of experience."
Chelsea were already 2-0 up when Alex Oxlade-Chamberlain handled an Eden Hazard shot and Marriner instead showed the red card to Gibbs, despite his team-mate apparently approaching the referee to admit wrongdoing.
"I believe it was handball but the referee hasn't seen it," Wenger added.
"The ball went out and I think it's Chamberlain who touched the ball.
"I don't know who gave indication to the referee that it was handball but he has certainly not seen it."