Arsenal manager Arsene Wenger says defender Mathieu Debuchy is "destroyed" after suffering his second long-term injury of the season.
The 29-year-old joined the Gunners during last summer's transfer window but was ruled out for months after damaging his ankle ligaments in the 2-2 draw against Manchester City in September.
And he will again be sidelined for three months after suffering a dislocated shoulder last week at home against Stoke City.
"He is destroyed because he is such a keen player, so professional, so willing," Wenger said.
"It is his first year here and of course he is embarrassed. But it is not his fault. He was pushed. The push was not needed.
"I watched it again and in that situation he was a bit unlucky as well because there is a little divot just after the touchline and maybe that made it worse.
"I just think that [Marko] Arnautovic had no chance to get the ball. I don’t think it was malicious but it was not needed because he had no chance to get the ball.
"I am not a specialist and these subjects are always very sensitive because I don’t really know what his intention was. It is difficult. It is not obvious. I don’t think he wanted to hurt him but it was not needed."
Asked if the Gunners will sign a replacement during the January transfer window, Wenger said: "We are out in the market and we are working very hard every day.
"All our scouts and our people are working very hard to find a defender."
