Arsenal manager Arsene Wenger has labelled Jack Wilshere's smoking as totally unacceptable and plans to take up the issue directly with the England midfielder.
Wilshere was pictured with a cigarette outside a London nightclub in the early hours of Thursday morning as players wound down following Arsenal's 2-0 win over Napoli earlier in the week, when the 21-year-old had started on the bench.
Wenger, whose side head to West Brom on Sunday looking to maintain their place at the top of the Barclays Premier League, will leave Wilshere in no doubt of his responsibilities on and off the pitch.
Speaking at Friday morning's pre-match media conference, the Arsenal manager said: "I disagree completely with that behaviour.
"I don't know really what happened, so I will need to have a chat with him about that.
"There are two things - first of all when you are a football player you are an example and as well you don't do what damages your health.
"The fact is that you can damage your health at home, you can smoke at home and you can drink at home, and nobody sees it, but when you go out socially you also damage your reputation as an example."
There have been many examples of top sportsmen who smoked, such as France international Michel Platini, who is now UEFA president, while Holland legend Johan Cruyff even regularly lit up on the sidelines when he was coach at Barcelona.
Wenger, however, accepts in England the culture makes such a position untenable.
"Yes of course things are different, in England especially," he said.
"You don't need to convince me because I must tell you, I travelled as a football player on coaches after games in France where you didn't see each other, there was so much smoke on the coach. Everybody smoked, but times have changed, and the health worry, the example, the role models from the football players request has changed as well.
"I must say as well, English society is very sensitive to smoking, much more than France, more than and southern (European) countries, so it is a bit more shocking here than it is somewhere else."
Wilshere had spoken of his desire to improve his own game after starting on the bench against Napoli, when club record signing Mesut Ozil scored his first Arsenal goal and then set up a second for Olivier Giroud as Arsenal swept the Italians aside with two goals in the first 15 minutes.
England manager Roy Hodgson has again called the combative midfielder into his squad for the crucial World Cup qualifiers against Montenegro and Poland.
Wenger has no doubts Wilshere remains an integral part of hopes for both club and country this season.
The Arsenal manager continued: "He is a very important player here, you know. All my plans for the future at the club have always been built with Jack and around Jack. We had some setbacks with him - a lot - but he is a very important player in my squad."
Arsenal head to The Hawthorns - where a young side came through a penalty shoot-out in their Capital One Cup tie last month - without full-back Bacary Sagna, who has a hamstring injury which will rule the France international out for the best part of a month.
"He will not be fit. He has a hamstring injury and will be out for the weekend and for basically three weeks," said Wenger, who is set to give England under-21 international call-up Carl Jenkinson another chance to impress.
"It is always a blow because he is a very complete defender. He can defend well, he is good in the air, he can attack well as well, and he's a winner-type, so of course for us it is a handicap
"But Jenkinson had a good start to the season as well and he is growing as a player. I am sure he will do very well."
Wenger is expecting a stern test of his side's form this weekend, when Arsenal will be out to record a remarkable 11th straight win in all competitions against a side on the back of an impressive shock away win at Manchester United.
"They had quite a strong side out (in the Capital One Cup) and many of the regular players played, but they have a big squad," Wenger said.
"I noticed when I looked at their team who played at Manchester United, that they have a massive squad of experienced players, so it's very difficult to predict who will play against us."
Wilshere's representatives maintained the 21-year-old was taking part in a "prank" where he agreed to hold the cigarette as part of a "dare".
The Arsenal midfielder responded on Friday afternoon by posting a photograph on his official Twitter feed of France World Cup winner Zinedine Zidane smoking.
He then followed it up with a post of "But for the record....I don't smoke!"