Wenger was appointed as Arsenal boss in 1996 and has led the club to three Premier League titles and four FA Cup triumphs, as well as final appearances in the UEFA Champions League and the UEFA Cup.
Arsenal have gone nearly nine years without a trophy, since a penalty shoot-out triumph against Manchester United in the 2005 FA Cup final, but this season sees Wenger's side challenging firmly on two fronts.
Ahead of Wenger's milestone game - at Chelsea on Saturday - Arsenal sit third in the Premier League, four points off their opponents in top spot, with an FA Cup semi-final against Wigan Athletic to come at Wembley next month.
Groves, who played for Arsenal for six years between 1986 and 1992, thinks that Wenger has firmly established himself as one of the club's greats.
"I think he's already an Arsenal legend," he told Perform.
"He's already up there as Arsenal's greatest ever manager."
Groves also highlighted the impact Wenger has had in changing attitudes, not only at Arsenal, but in English football.
He added: "I'm a big fan because not only did he change the culture at Arsenal - the culture of the football and the philosophy there - he also changed the culture in English football in general.
"When he came in, there was a big drinking culture at Arsenal and at other clubs.
"He completely knocked the drinking culture on the head and made it clear to the player that if you want to be an athlete and prolong your career, the alcohol wasn't going to be in the equation.
"He changed diets, he changed physiology, he changed psychology, he was more on the sports science side and when he came in he was probably about 10 years ahead of everyone."
