Veteran centre back William Gallas has been praised by boss Arsene Wenger for his influence on Arsenal's new-look defence.It has certainly been quite a transformation for the former Chelsea man, who this time last year was stripped of the Arsenal captaincy after publicly questioning the mentality of Wenger's young squad."William Gallas has had a fine start to the season, which is down to both his attitude and the quality of the player," said Wenger."It can happen that any player has highs and lows in his career, but I must say his form now is a consequence of the way he behaves every day."He behaves 100% as a professional and is highly focused in training."The Frenchman indicated he will look to discus a new deal for Gallas, 32, at the end of the year as from January the defender will be free to talk to other clubs."The partnership between William and Thomas Vermaelen has gelled more quickly than I expected," the Arsenal boss said."This is for two reasons; first of all, Vermaelen adapted faster, and secondly William fits more comfortably on the right side of a central defence than on the left."