The German pair are set to start tonight against Champions League opponents Borussia Dortmund.
"Mesut has a special feeling for where space is, and for giving the right pass. He goes deep, begins a triangle: the players know that you can play with him," said Mertesacker.
"Mesut is someone who can work well instantly. That kind of talent you cannot buy. He actually plays for Arsenal like he's been many years here, so I was not worried about him when he came."
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