Arsene Wenger admitted he has major concerns after injuries to Alex Oxlade-Chamberlain and Theo Walcott left him with a mounting casualty list heading into a crucial 10 days of fixtures. The England duo were both forced off in the opening 20 minutes as Arsenal crashed out of the Capital One Cup fourth round stage at Sheffield Wednesday on Tuesday evening. Two of the few senior players on show, Oxlade-Chamberlain first went down clutching his hamstring, before being replaced by Walcott, who just minutes later suffered an apparent calf complaint.

“They are two muscular injuries, how big the damage is I don’t know because we have to wait 48 hours to check on the scan and see how big the damage is,” he told Arsenal’s official website after the 3-0 defeat at Hillsborough.

Wenger rued the absence of two experienced players to a lineup that was left with three debutantes and were comprehensively defeated by their Championship opponents. But by far his biggest concern was the impact the injuries could have on the club’s performances in what Wenger considers the more important competitions of the Premier League and the Champions League. Arsenal will visit Swansea City on Saturday, before facing a crucial Champions League clash at Bayern Munich on Tuesday and then four days later hosting Tottenham in the north London derby.

“We knew at the start of the game that if something happens to us we were a bit short,” he told Sky Sports. “But we have to manage the workload of the players. We left six players at home and I think I did well when I look at the two players who got injured today.

“We are short now because we lose Chamberlain today, we lose Walcott. And we already have a few injuries. It is a big blow for us today, of course to lose the game but even more for the other competitions that are very important for us, to lose two players of that stature.”

Wenger’s comments certainly suggest that he is pessimistic of the injured duo being fit to return at least for the trip to Wales this weekend. And, with muscular injuries generally taking at least a couple of weeks to heal, the Arsenal manager is likely to be left with major selection headaches for some vital matches. Reports suggest that both will miss the next three matches.

Walcott has started to impress in the central striking role, but, with Danny Welbeck out until January, his absence would leave Olivier Giroud as the only fit senior striker. Joel Campbell, who started but failed to make an impression on Tuesday and has yet to score a goal for Arsenal, would be the next likely option. Alexis Sánchez could also be moved into a central role.

Wenger, though, has major problems in midfield. Already he is missing Aaron Ramsey, Jack Wilshere, Tomas Rosicky and Mikel Arteta to injury. If Oxlade-Chamberlain and Walcott are out, Wenger could decide to move Santi Cazorla forward into a right-sided midfield role, bringing Mathieu Flaimini into his position in the middle. Otherwise Campbell could be brought into the mix, despite having yet to start a single game in either the Premier League or Champions League for Arsenal. Potentially, too, Hector Bellerin may move forward from right-back, with Mathieu Debuchy stepping in.

Either way, it would mean a disruption to what had been a winning formula of late. Before the loss to Sheffield Wednesday, Arsenal had won four matches on the bounce to move level with points with Manchester City at the top of the Premier League and keep their hopes alive of making it to the Champions League knockout phase.