Per Mertesacker has agreed a contract extension at Arsenal, the club have confirmed.
"He is a leader of the team and he is also one of the four centre backs who has experience and can guide the team," Arsene Wenger told Arsenal Player.
"There were no negotiations in fact, because he had an option for extension. So it's not really a new contract, it's just an extension of the old one. We had to take that option early in the season and the decision was made quite easily.
"On the pitch he has his own technical attributes, that is his reading of the game, his intelligence, his guidance. He's good in the air because of his size.
"Mentally, he's a guy who brings a level of urgency into the team, a level of focus, a level of desire to do well and he's very demanding with the people around him. He's very respected as well and that's why he gets a lot from the players around him.
"I've never seen a training session where Per was not fully focused to do well. That's why he has improved with us a lot on a technical front, because his focus is always 100 per cent."