Arsenal vs Borussia Dortmund: Jack Wilshere 'ruled out for a while' as Arsene Wenger confirms midfielder needs to see specialist Wenger confirmed that Wilshere would be "out for a while" after coming off during the 2-1 defeat by Manchester United on Saturday after feeling some discomfort. Wilshere, who was replaced by Santi Cazorla in the 55th minute of the game at the Emirates Stadium, will therefore miss the Champions League clash with Borussia Dortmund on Wednesday. Wenger did confirm, however, that Laurent Koscielny is back in the squad following an Achilles problem and Danny Welbeck is expected to be included, although striker Olivier Giroud is not registered and Theo Walcott is still ruled out. Wenger admitted concern over Wilshere's injury, although X-rays after Saturday's match indicated there was no bone break. I cannot give you any time schedule there because he will be out for a while and he has to see a specialist next week to see how long he will be out. We don't know at the moment," said Wenger at Tuesday afternoon's press conference. Read more: Arsenal fan sees red and pours wine over United bench Podolski makes it off the bench to go to Winter Wonderland Wenger's principles questioned by Usmanov He has a big ankle sprain and I don't want to talk about it because I am not a specialist medically. [To find out] for how long, we will need to see a specialist. Wilshere is tackled by United defender Paddy McNair Wenger, though, believes the return of France international Koscielny will boost the Gunners' rearguard, which was brutally exposed by United on the break. He's in the squad for tomorrow. It's very good news because he was out for a while now and we are short in numbers defensively. It's good to have his quality back," said Wenger.