The Japanese youngster is still adjusting to life in England.
Wenger told arsenal.com: "Ryo is a guy with heart. I don't think he played long enough and we were in a position where we had to defend more than we could attack. But you could see straight away that his heart, his determination and his pace in the game are big assets.
"He is like Oxlade-Chamberlain - they have to get used to the intensity of these games. When will he be ready? He just had one day training yesterday with the group because he was injured. He worked a lot with the fitness coach. I believe he will be ready at Christmas."