Arsenal manager Arsene Wenger says holding midfielders Mikel Arteta and Francis Coquelin have both suffered an injury against West Bromwich Albion.
The Gunners suffered a surprise defeat at the Hawthorns as they lost the first place in the Premier League.
And more bad news followed as they lost two players in the same position due to injury with both expected to be assessed later on Sunday.
"We have two more injuries," Wenger revealed.
"One is a muscle problem for [Mikel] Arteta and the other one is a knee problem and I don't know how serious that is but we will know certainly tomorrow, for [Francis] Coquelin. Arteta is a calf.
"[The mental state of Giroud and Koscielny?] We are competitors, I believe in life they are disappointed like I am. Once your are in the competition you are in the competition, you have to be professional.
"I fought my whole life to know that when I am at work I am at work, when I am outside work I am outside work. That is what it is about.
"How much [Paris] affected them, I don't know. I can only speak for myself. Our best players today, like Alexis, he flew back Thursday night and was not tired at all.
"They were highly focused and had the desire to play. I just want to say when you are on the pitch, you are on the pitch."