Arsène Wenger has bemoaned the weight of expectation on Jack Wilshere, insisting the Arsenal midfielder must be allowed time to build his fitness after a series of injuries in the past two years.

Wilshere, widely criticised after being pictured smoking during a post-World Cup holiday in Las Vegas, was defended by Wenger after a largely anonymous performance against Crystal Palace on the Premier League’s opening day, which ended with his substitution after an hour.

The Arsenal manager dismissed suggestions that Wilshere had been too slow to build on his reputation as one of England’s most promising young talents, saying pundits were routinely too quick to criticise young players for failing to realise their potential.

He said: “Wilshere has paid the price for England not winning the World Cup! Before he was in [Calum] Chambers’ position, then suddenly when you get to 22, the expectation level comes on you. Rooney has gone through that, now Wilshere goes through it.

“I believe at the moment he should not respond to it, just focus on his game. If Wilshere can maintain his physical fitness then he will make a huge career. At the moment, I believe he should just focus on being fit, present and to improve physically. The rest will come along.”

Wenger said the key to the midfielder’s progress would now be to block out external pressure and to focus on building his performances and strength game by game. “I have told him the target is for him to have the whole season being available to play. I think he is on target in terms of where he should be. Yes, he [has not developed] as far as everyone expected him to from when he was 18, but that’s because he was injured, not because he doesn’t train seriously. He is a guy who wants to play, he works hard – but he was out for one and a half years.”

Paul Scholes has been among Wilshere’s more high-profile critics. The former Manchester United midfielder said in May that his progress was lagging, prompting Wilshere to phone him for an explanation.

“We had quite a good chat,” Wilshere said at the time. “He is entitled to his opinion. I just wanted to know…If it had come from a less respected player, I could say, ‘What are you talking about’, but it came from Paul Scholes. So I wanted to get to the bottom of it.

“He was right, in a certain way. When I burst on to the scene there was all this noise [about me] and then I got injured. But there comes a time when you stop being a kid.”