The Swiss midfielder joined the Gunners from German club Borussia Monchengladbach for in excess of £30million earlier this summer and his arrival in North London certainly has German defender Mertesacker excited ahead of the new season.
"I don't know him personally but that doesn't matter, we will get along with each other very quickly because he is a good player and has done so much for Borussia Monchengladbach," Mertesacker told Arsenal Player.
"He can speak German as well, so it will be joy to get his first year going and help him bed in as a player.
"He's a leader and that is really important, especially in midfield. He has got a very good attitude, is very composed on the ball and contributes a lot.
"He is a good passer as well, so he will set the tempo. I am looking forward to how he does it, how composed he will be in training and in the games.
"He will be the perfect signing for us."