Diaby was awarded man of the match after a superb display at the heart of the Gunners' midfield in a 2-0 win at Anfield on Sunday.
Wenger hailed the Frenchman's efforts to recover from prolonged injury problems and believes that he can be a key component in a new-look Arsenal team this season.
He said: "You can see it is massive for us because he is a tremendous football player. He has absolutely everything you want in midfield.
"He hasn't played for a year but he had a good pre-season where we had him 45 minutes every three days and now he looks in good shape. There is more to come from him but what he has shown today is very good.
"I was worried about him highly but I always stood behind him because not only is he a fantastic football player but a fantastic guy as well."
Diaby has been called up by France manager Didier Deschamps for next week's World Cup qualifiers against Finland and Belarus.