It’s a familiar, frustrating story for Arsenal supporters. A mid-season injury crisis threatens to derail the club’s hopes to land a first Premier League title since 2004. In a championship more wide open than has been seen in several years, Arsenal have taken just one point from their last two matches, against West Brom and Norwich City. Although they still lie fourth in the table, only two points off the top, it is hard not to look at the past week as a major opportunity missed for Arsenal to truly assert their authority on the title race.

And even more worrying for Arsenal, the slip-ups have come amid an ever-growing injury crisis. Even before Sunday’s 1-1 draw at Norwich City, Arsene Wenger was missing a host of players, including Theo Walcott, Francis Coquelin, Jack Wilshere and captain Mikel Arteta. But the clash at Carrow Road saw three more players go down, all of them influential. Laurent Koscielny and Alexis Sánchez were both forced to go off with injuries, while Santi Cazorla, although he finished the match, was described as having “played on one leg,” by Wenger after suffering a knee problem.

Of the three, only Koscielny looks to have a chance of featuring when Arsenal will seek a vital three points at home to Sunderland on Saturday. And both Sánchez and Cazorla also look set to miss Arsenal’s decisive final Champions League group game at Olympiakos next Wednesday. It has been confirmed that Cazorla has suffered knee ligament damage, while Sánchez injured his hamstring and looks set to miss at least three weeks.

“He says it’s a kick on his hamstring. I fear that’s not really the reality,” Wenger said about Sánchez’s problem after Sunday’s encounter.

The latest spate of injuries has only cast fresh light on Arsenal’s frequent difficulties in keeping their key players fit. The situation is highlighted by the injury to Sánchez. The forward has hardly had a break of any kind in the past two years, having played in the 2014 World Cup with Chile, and this summer leading his country to the Copa America title. Wenger had said that Sánchez would be able to sit out the start of the season in order to get some much-needed recovery time, but instead he was used off the bench in Arsenal’s opening Premier League game against West Ham.

In the lead up to the match with Norwich, Wenger even admitted that Sánchez had experienced, “a little hamstring alarm.”

Yet he made his 24th appearance this season for club and country at Carrow Road, and duly suffered the injury that is now set to sideline him during a crucial phase of Arsenal’s season. Once more, it appears to be a case of Arsenal’s thin squad being already stretched by injuries, leading to Wenger putting undue stress on those players remaining, and resulting in yet further injuries.

There is at least some good news on the injury front. Walcott, who suffered a calf strain in a Capital One Cup defeat to Sheffield Wednesday at the end of October, could be in contention for a place in the squad against Sunderland.

The side still promises to be severely depleted, however. With Cazorla and Sánchez out, Wenger would likely move Aaron Ramsey alongside Mathieu Flamini in midfield, with Joel Campbell and Alex Oxlade-Chamberlain flanking Mesut Özil behind Olivier Giroud.

And, while Sunderland have in recent years been seen as something of a pushover, there is reason to think that they could give Arsenal more of a challenge on Saturday. Under new manager Sam Allardyce the north-east club have climbed out of the Premier League relegation zone, having won successive matches for the first time this season.