"Mesut can play football, that is what his aim is to be here to do, so it is just the little details," Mertesacker said.
"It is things like how to get on (in London), how to come to the training ground, to get to whatever he wants to go. It is just a quick call or a text, you can help him out.
"I need to (help Ozil settle), because it is very important to get him into the squad quickly, so that he can adapt and play with freedom.
"That is what he is - his vision is enormous and with him we are more dangerous and can compete at the higher levels.
"We try to make it comfortable for him to adapt as quickly as possible and it fits.
"Against Napoli, you felt that he could play 90 minutes on a high level, he can make the difference at any time in the game.
"We are delighted to have him here and to help him to get into the team. He has shown that he respects our game and that he does fit in.
"We can expect a lot (more) from him in the coming weeks, you could see that we needed his contribution and he is the right addition."
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