Jack Wilshere could face ankle ligament surgery and a lay-off of around three months. The Arsenal midfielder will meet with a specialist in the coming days and the decision will be taken as to whether he needs the operation to repair the damage to his left ankle that he suffered after a challenge from Manchester United’s Paddy McNair on Saturday.

If Arsenal feel that Wilshere can be fully rehabilitated without the surgery, he would be back in action sooner but he would still most likely miss around eight weeks. It is a tough blow for the England midfielder, who had found form for club and country, and he will now begin the familiar process of considering the long road back to fitness.

Arsenal are clinging to the hope that, like Olivier Giroud, who returned as a goal-scoring substitute in the 2-1 loss to United weeks ahead of schedule after fracturing his tibia in late August, Wilshere could yet surprise people and make a speedy recovery.

But it did not take long in the company of Arsène Wenger on Tuesday to feel that it was wishful thinking. The Wilshere update cast a shadow over the club’s preparations for Wednesday night’s Champions League home tie against Borussia Dortmund, in which they need a point to ensure their progress to the next phase of the competition for the 15th year in succession.

Wilshere has been plagued by ankle injuries since his first full season with Arsenal in 2010-11. It is often said that the right ankle is the problematic one – it cracked in the summer of 2011 and forced him to miss 17 months of football – but the left one has not been without its difficulties, initially, as a result of Wilshere over-compensating to protect the right side. It was that which rolled in grisly fashion under McNair’s tackle in the 52nd minute on Saturday.

As usual, Wilshere attempted to continue after treatment. His pain threshold is high and he is always determined to play, no matter what. But in the 55th minute, he sat back down on the turf and was forced to admit defeat. It is unclear as to whether Wilshere made the problem worse by carrying on. He left the field and, indeed, the stadium afterwards under his own steam, without crutches or his foot in a protective boot.

Wenger stopped short of castigating McNair but it was clear that he felt the 19-year-old had erred with the decision to lunge in on Wilshere. “I don’t think it was a tackle with the desire to hurt, I think he went for the ball but it was a late tackle, a tackle which a young player can do,” Wenger said. “It was a bad foul.”

“The tackle caught him from the side, just when Jack had moved the ball forwards too much. When he dived to make the pass, McNair came in to make the tackle and took him from the back and the side. When you see the picture, it is very bad. There is no bone damage; we knew that straightaway after the game but there is ligament damage. It does not look good.”

Wenger will also be without goalkeeper, Wojciech Szczesny, against Dortmund because of the hip injury that forced him off against United and the winger Theo Walcott, who continues to feel a groin problem after his long-term absence following cruciate knee ligament surgery. With the back-up goalkeeper, David Ospina also out, Wenger will turn to the inexperienced Emiliano Martínez.

Danny Welbeck is a doubt with a minor knee injury and he did not train on Tuesday, although Wenger will name him in the squad while Olivier Giroud is ineligible, having not been named on the Champions League list as he was not expected to be fit until the New Year. This rather sums up Arsenal’s fortunes at present, in which even the positives – such as Giroud’s recovery – carry stings.

The sense of crisis has once again built around the club after the previous three results – the 3-3 home draw against Anderlecht, when they blew a 3-0 lead; the 2-1 defeat at Swansea City, in which they had also led, and the United reverse. But Wenger, who is the target of disaffected supporters, was in relaxed mood and he insisted that the quality in his team would show.

“When you are such a long time in football as I am, you don’t understand anymore what crisis means,” Wenger said, with a smile. “I must get to the dictionary and look at it well again. There is life in our team, there’s a dynamic in our team. I’m long enough in the game to know if there’s something there or not and there’s a lot there. This is one of the best teams I’ve had for a long time.”

Wenger said that Laurent Koscielny had made a surprise return to training after his trouble with tendinitis in his achilles and he would be in the squad while Aaron Ramsey believes that he is finally over his injury problems. The midfielder has struggled for form this season but he suggested that a nagging hamstring issue had been partly responsible.

“The Manchester United game was the first time that I felt physically sharp and I could recover a lot better after my runs forward,” Ramsey said. “I’m still going to make my runs into the box because that’s my game. But when I got forward [against United], I could get back in time as well.”