Arsene Wenger hit out at Steve Sidwell for the reckless tackle that earned the Fulham midfielder a red card in Arsenal's 1-0 win at Craven Cottage.
Sidwell will miss Fulham's last four games of the season after he saw red for the second time in two appearances.
The midfielder caught Mikel Arteta on his standing foot with a two-footed lunge just 12 minutes into the London derby at Craven Cottage.
Wenger's men also ended the game with 10 men after Olivier Giroud caught Stanislav Manolev with a last-minute challenge.
The Gunners boss had no doubts about either sending off, and said he believed Sidwell's challenge could have seriously hurt Arteta had it happened fractionally earlier.
"I think the referee could only give a red card [to Sidwell],'' he said. "We will see [if Arteta is OK]. He played the second half. I don't know how much damage is done. It is a kick, a bad kick.
"I don't know if he has twisted his ankle or not. In these kind of things, it is a question of a fraction of a second. If you are fully on your foot at the moment you get it, you break your leg."
Fulham boss Martin Jol said Sidwell, 30, deserved to go, explaining: "I can't defend him, because that would only sound ridiculous.
"I was annoyed with him, but he says it is not intentional. He will regret that tackle. It was the first foul that spoilt the game
"I know it was not intentional because he wanted to play. He has just come back from a three-match suspension and now he is out for another four matches again so it was not only disappointing him, but also for us because we had to play with 10 men for a long time.''
Despite the setback of losing Sidwell so early in the game, Fulham coped admirably, continuing to probe the Arsenal back four thanks to impressive performances from Urby Emanuelson, Eyong Enoh and Alex Kacaniklic.
They were left exposed at the back, however, and Per Mertesacker took advantage to score just before half-time.
But in the end, the Gunners were left hanging on for the win that moves them back up to third in the Premier League table.
"It was tight in the end as we couldn't score the second goal,'' Wenger said. "I believe we became cautious in the second half. Our first half was quite good, we were in control, and we played well.
"I don't know what happened in the second half, whether it was a physical or mental thing
"The final 10 minutes were really nervy. They started to play direct, in the box they had a few dangerous balls, and it was difficult. Still, it is a very important win for us.''
Information from the Press Association was used in this report