That vital clash precedes Wednesday's Champions League Round of 16 encounter with reigning champions Bayern Munich and although it is a hectic time, Mertesacker feels the north London club are up for it.
"We have big challenges in front of us," the German centre-back told talkSPORT.
"But we have to try and isolate each game - that is the key for us at the moment. I feel now that we are mentally strong enough to cope with this situation.
"When you know that February could be season-defining, it makes you feel like you need to always be at your top level and putting in your best performances. You feel the tension before every game - but before big games and big opponents you do feel it a bit more within yourself.
"We have a young squad, but it's one with plenty of experience. And I feel that, mentally, we are strong enough to cope with those situations better than maybe last year or two years before. We have to isolate each game. So we take the next game against Liverpool, which is very important in the FA Cup, and make sure all the other things are far away - that is the key for us at the moment."
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