Arsène Wenger does not seem to believe that where there is smoke there must be fire. Of course he expressed his disapproval after a photograph appeared in a newspaper showing Jack Wilshere with a cigarette in his mouth in the early hours of Thursday morning, but the Arsenal manager's demeanour did not suggest he fears the midfielder's lifestyle is descending irretrievably into decadence.

Certainly Wilshere's agent said there is nothing to worry about, explaining that the 21-year-old had been merely taking part in a "prank" and had held the cigarette as "a dare", while the player himself remained in waggish spirit when he took to Twitter after the publication of the story and posted a photograph of the France World Cup winner Zinedine Zidane puffing away. "But for the record .... I don't smoke!" added Wilshere lest playfulness be construed as recklessness.

Wenger vowed to get to the bottom of what happened but his tone was that of a man who suspected this was a forgivable lapse by a 21-year-old.

"I disagree completely with that behaviour but I don't know really what happened, I need to have a chat with him about that," Wenger said. "There are two things: first of all, when you are a footballer you are an example, and [secondly] you don't do what damages your health. You can damage your health at home, you can smoke and drink at home but nobody sees it, but [it is even worse] when you do it in public, as you damage your reputation as well."

Wenger would not disclose what he intended to say to Wilshere during their "chat" but it is a safe assumption that he will remind the player of his responsibility to himself and the club. However, he did not appear to believe Wilshere smokes regularly – joking that England can count on the midfielder to perform well in this month's World Cup qualifiers "even if he had had one cigarette".

There was a time when Arsenal seemed overly dependent on their precocious midfielder but the arrival of Mesut Özil, the return of Mathieu Flamini and the resurgences of Aaron Ramsey and Tomas Rosicky mean matters relating to Wilshere no longer provoke extreme reactions. Arsenal have excelled this season without starring contributions from Wilshere, who has started only four of the team's six Premier League games and was not introduced to Tuesday's night's Champions League victory over Napoli until the game had been won. The quality of Arsenal's squad, then, has allowed Wenger to take some pressure off Wilshere, whom he says remains a key player for the club even if he is no longer a certain starter.

"All my plans for the future at the club have been built around Jack and with Jack," Wenger said. "We have had some setbacks with him, a lot, but he is a very important player in my squad. He will play. But there is competition for places of course. On one side, people want you to have good players, on the other, that means you cannot give any guarantee to anybody."

Wenger says the fact that Wilshere has frequently been deployed out wide this season rather than as the central playmaker does not mean his influence is waning. He believes Wilshere is more effective out wide or in a deep role rather than as an advanced schemer. "Higher up [the pitch] he is less comfortable at the moment. He doesn't like to have his back to goal, he likes to face the game. Why? Because he has a burst to pass people with the ball at his feet. From deep he does that very well, he creates the openings for that little burst to run with the ball.

"He is a physically strong boy, he has a good body. He can win the challenge and make the difference and open the game up. He is getting that burst back now [after various injuries over the past two years]. I think to play on the flanks helps him to find that back, because on the flanks you have to do a lot of that."