Arsenal goalkeeper Bernd Leno took to social media hours after his mistake in the 2-1 defeat to Chelsea.
The Gunners looked on course to hand new head coach Mikel Arteta his first win, after Pierre-Emerick Aubameyang's first half header.
But Chelsea scored two late goals to condemn Arsenal to their fourth straight home defeat in all competitions.
Leno was badly at fault for the first goal, after misjudging the flight of the ball and failing to claim the ball, leaving Jorginho to tap into an empty net.
Tammy Abraham went on to score a winner four minutes later, finishing off a counter-attack after a cutback from Willian.
Speaking after the game, Arteta refused to blame Leno and said the squad will rally behind their number one keeper.
"He will be down, and when an error costs the team points we have to lift him," the Arsenal head coach said after the game.
"He's done a really good job since he joined this football club and we have to respect that.
“We just need to bring the confidence back in and that's it.”
After the match, the German international tweeted: 'Very tough day today, but I have to look forward.'
The post prompted Arsenal supporters to respond, with one writing: 'No worries it happens. Don’t let it get to you too much,' while another wrote: Forget about it brother saved us enough this season.'
Former Wolves goalkeeper Matt Murray was a pundit for Sky Sports during the game and he explained what Leno did wrong.
He said: “I said before how much I rated Leno, but he'll be very disappointed.
“He comes for it and decides to come and punch. He should have an open hand as I believe if he does, he would have got a touch on it.
“Leno has to keep his concentration. He decides to come and punch it to protect the goal.
"If he opens his hand, he has that slight bit more, an inch which would've allowed him to get to the ball. He's panicked at a crucial moment."
