Per Mertesacker believes Arsenal's failure against Southampton on New Year's Day was down to their lack of reinforcements in defence and inability to rest key players.
The German international has been involved in every game that the Gunners have played in the last few months and is struggling to cope with the amount of pressure that he is being burdened with.
The Gunners have taken six points from their last three games and with the January transfer window upon them, need to bolster their squad to help them in the Champions League and defend their FA Cup title.
Mertesacker also talks about Laurent Koscielny who has been nursing a chronic Achilles problem and has only returned to first team action after a lengthy lay-off. The German believes that Koscielny failed to live up to his desired level against the Saints as he had been rushed back from injury without enough training to back him up.
The situation was aggravated by Arsene Wenger's inability to replace Thomas Vermaelen, who was sold to Barcelona.
The Frenchman is likely to be rested for the FA Cup game alongside Mertesacker with Calum Chambers and Nacho Monreal expected to come in to the centre-back positions.
"For example Laurent, he has to play. He cannot train for two or three weeks because we have no players left. It's always tough at the moment. Players come back and they have to play immediately," Mertesacker said.
"We have a big squad but, obviously, we need fit players. That is our main target. We could do with a small break but we haven't got a small break so we need to prepare ourselves for Sunday again. As I said, I'm pretty sure that we will come back.
"At one point, you want to be consistent in your line up, especially the back four. We haven't had that through the season. We have to find that. It's difficult for us at the moment.
"What keeps us going is our spirit and out belief in our squad because we have a big squad, suffered a lot of injuries. We will bounce back, I'm pretty sure we will come back because of our team and spirit, we never give up no matter what happens that is my feeling.
"We were just not good enough at Southampton [on New Year's Day], we came from two good wins but, in 2015, we have to realise and remind ourselves every day that we need to be at our best especially away from home," he concluded.