The Frenchman remains confident that he has an attack capable of seeing off the challenge of Besiktas and securing a place in the group stages of the Champions League following a goalless first leg.
"When you don't score people are critical about goals and I agree with them, but we had chances and having watched the game again I believe we had the chances against Besiktas and much more than we had against Crystal Palace [in their opening Premier League game]," Wenger is quoted as saying by talkSPORT.
"Joel Campbell can contribute to that. At the moment he has not got his chance, but he will get it."
Costa Rica international Campbell was recently the subject of an approach from Liverpool.