Mertesacker hoping Wenger can add to Arsenal squad
Mertesacker says the squad needs strengthening to be a title challenger.
"We haven't sold any players yet so we are coming from a good base at the moment, we're at a good level and no-one is leaving at the moment.
"It's a big year for us. We've got the World Cup at the end of it but the focus has to be on Arsenal because, of course, we want to win things and be successful this year."