The Germany international has been outstanding for the Gunners this term.
Mertesacker recalled: "I went through a lot of difficulties and a lot of mistakes at the beginning, but the manager always said I would get through it because I was a good player.
"I took my time to settle down completely and there were a lot of reasons.
"I missed completely the pre-season (before joining Arsenal), so it was really hard because I had to work straight away to play straight away.
"It took me a while to get to that level, but the manager always trusted me and said I was intelligent enough to cope with problems.
"Then I got a big injury in my first year and I missed Euro 2012, so I was fit for my second season.
"Maybe it was a good thing that I missed the competition with Germany to train and get my body fit."
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