Arsène Wenger believes Yaya Sanogo has become a “different animal” since undergoing an intensive four-month rehabilitation regime.

The 21-year-old joined Arsenal on a free transfer from Auxerre last summer, and featured twice in August before a lengthy absence.

The French striker has started the last two matches, against Liverpool and Bayern Munich, and Wenger believes he is starting to show his potential.

In pre-season he was under-strength and not ready muscularly. We decided to take him completely out and try to build him up for four months - two months in France and two months with us

Arsène Wenger

“When I first knew of him, he had not played. He had been out for two-and-a-half years,” the manager said. “At 16 years of age he was a very promising striker.

“He started to play a little bit at Auxerre last year and I got alerted by [scout Gilles] Grimandi that he was playing again so I sent him to watch him. He said he could be interesting.

“Then I met him and we had a long chat about what happened to him and I decided to try to take him. He called me back and said, ‘Look, I will join you’. He had had one or two more offers in France and I knew it was a going to be a building process of six months.

“In pre-season I saw he was under-strength and not ready muscularly. We decided to take him completely out and try to build him up for four months - two months in France and two months with us. When he came back on January 1, I saw he was a different animal.”

Wenger believes Sanogo has plenty of raw potential, but says he must work extremely hard if he is to fulfil it.

“He is very, very ambitious and believes in his quality,” he said. “He is very passionate and naturally has a great desire. You can see that in games. He is ready for a fight.

“When you look at his stature, he is a similar shape to Giroud but you feel there is a lot more to come out with him. He has a lot of improving to do. But you have to be open-minded. If he does well, he will play. If he doesn’t, he won’t.

He is very passionate and naturally has a great desire. He is ready for a fight

Arsène Wenger

“I believe up front that it's not experience that decides things. At the back, it's different. But up front it's an instinctive job. Experience helps a little bit. But the belief, the confidence, is more important up front than the experience.

“When I started to play Anelka, everybody said: 'Why do you start Anelka, why not buy a striker?' We won a championship with him. It's just like that, if we feel they are ready then they play.”

Copyright 2014 The Arsenal Football Club plc. Permission to use quotations from this article is granted subject to appropriate credit being given to www.arsenal.com as the source Rob Kelly 21 Feb 2014