Arsene Wenger has confirmed a double defensive blow forced him to play Francis Coquelin at centre-back in a 3-4-2-1 formation against Manchester City on Sunday (5 November).
Arsenal lost 3-1 to Pep Guardiola's side and French midfielder's selection was one that was questioned after the game as he did look out of his depth during the course of his 56 minutes on the pitch.
Wenger is without Shkodran Mustafi, who is injured at the moment and will only return after the upcoming international break. The French coach had used either Per Mertesacker or Rob Holding at centre-back in recent games alongside Laurent Koscielny and Nacho Monreal, while Mohamed Elneny has been used for games in the Europa League and the EFL Cup.
Coquelin did not fulfill his role in the first-half and was substituted after 56 minutes to make way for Alexandre Lacazette as Arsenal returned to a back four for the remainder of the game. Wenger has since revealed that an injury to Holding and Mertesacker taking ill were the reasons for a sudden change.
"I can explain to you that Mertesacker came into training yesterday morning, sick. That Holding had a thigh strain. That Debuchy had just come back from [being] a long-time absentee," Wenger said after the loss to the title favourites, as quoted on Arsenal's official site.
"That I don't see that big a problem to play in the middle of the [central defensive] two. You're a defensive midfielder or a defender, it's exactly the same. I don't think that was a problem in our game," the Gunners boss added.
Arsenal's fourth loss of the season sees their title hopes all but extinguished as they are currently 12 points behind City. They also face a battle to finish in the top four with Manchester United, Tottenham Hotspur and Chelsea the favourites to take the next three spots on the Premier League table.