Coach Mikel Arteta said it is a “big shame” Arsenal will be without captain Pierre-Emerick Aubameyang for three games after his ban was upheld.
The Gabon striker, 30, was booked for a tackle on Max Meyer in the 1-1 draw at Crystal Palace but the video assistant referee overturned the decision.
Arsenal appealed against Aubameyang’s red card but his suspension will stand.
“It’s a big shame and a big loss for us, but he mistimed the tackle and we have to accept it,” said Arteta.
“It’s an action that is completely accidental, in my opinion. He’s been superb under me, he’s working so hard. He’s scoring goals and has probably been the most important player so to lose him is really bad news for us.
“Players have to step up. You know, when one of your big players is not there, they have to take responsibility.”