Arsène Wenger returns to a familiar stage against Dinamo Zagreb tonight, when he leads Arsenal into their 18th consecutive Champions League group phase campaign. But it was another well-worn storyline that deepened his worry lines in the Croatian capital and dominated his media briefing.

Back in London, Jack Wilshere was facing up to yet more surgery and yet another lengthy injury lay-off. When Wenger said last week that he had suffered a setback in his rehabilitation from the hairline crack to the left fibula that he suffered on the eve of the Community Shield, you almost knew – given his wretched luck – what would come next.

The club duly confirmed the bad news yesterday afternoon that Wilshere would need the operation – which will involve a small metal plate being inserted into the fibula – and would be out for around three months.

Basic logic

Wenger tried to be positive, to make all the right noises about there being plenty of the season to go; how this latest difficulty was simply to do with the bone and, crucially, was “not linked with the injuries he had before”. In other words, the ankle problems that have blighted Wilshere’s career.

The midfielder is only 23, but there was a moment when Wenger made an admission and, although he repeatedly said he was not a medical specialist, it seemed to chime with basic logic. “When you are coming back from an injury, you have a vulnerable period, a time when you need to strengthen your body and gain competition,” Wenger said.

Wilshere has had so many injuries and it has come to feel as if he may have a weakness in his ankles or the bottom of his shins, although Wenger was quick to dispute this and return to the more positive line.

“I hope that Jack’s body stabilises,” he said. “I am confident it will and he will make a career of the kind he deserves. It’s just a part of his bone that has not healed. This kind of injury is not career-damaging.”

Wilshere will be confronted by a familiar set of psychological obstacles and, unsurprisingly, he is down at the moment. Club captain Mikel Arteta, who is expected to return to the starting lineup as Wenger tweaks his team with an eye on a heavy programme over the next 2½ weeks, said Wilshere's team-mates had to work on keeping him upbeat.

“We know he cannot waste his talent, because he has an amazing career ahead of him,” Arteta said. “We are responsible for putting that into his head every day and not allowing him to fall down because at some stage, that is the danger – that he does not believe in himself or his body.”

Unbeaten run

Wenger is determined to open positively against a Dinamo team that battled through three rounds of qualifiers – they are on a 41-game unbeaten run – but have not won a group stage tie in 15 attempts. Uefa’s changes to the competition’s draw system meant that Arsenal lost their status as top seeds and, having got

Bayern Munich

in the group, they can ill afford to slip against Dinamo.

“To beat them we have to play at our best,” Wenger said. “You are quickly out in the Champions League if you do not start well.”

Wenger has rested Héctor Bellerín and Aaron Ramsey which means he will make at least two changes to the team that beat Stoke City at home on Saturday, when both started. As expected, Per Mertesacker was also left behind – the defender has a viral infection – and Wenger faces a difficult decision between Olivier Giroud and Theo Walcott up front.

Wenger was asked about his previous visit, when his team beat Dinamo 3-0 en route to an aggregate 5-1 Champions League play-off win in 2006 but it was more recent memories that coloured his thoughts.

"If we missed one game in last season's Champions League, it was Monaco at home," Wenger said of the tie that led to Arsenal's elimination. "The drive to win this tournament is immense but I am long enough in the game to be realistic. Let's put the hard work in. We are ambitious but we are not dreamers." – (Guardian service)