Arsenal supporters were left holding their breath when Francis Coquelin hobbled off injured in Saturday's 2-1 defeat by West Brom, and their worst fears were confirmed when Arsene Wenger revealed he is facing "at least two months" out on Monday.
The 24-year-old joins the likes of Jack Wilshere, Danny Welbeck, Theo Walcott and Alex Oxlade-Chamberlain in Arsenal's crowded treatment room, and his injury is a particularly heavy blow to Wenger's side.
Coquelin has emerged as a key player for Arsenal since being recalled from a loan spell at Charlton in December last year. The tough-tackling Frenchman has added steel to a lightweight midfield and formed an effective partnership with the ball-playing Santi Cazorla.
Arsene Wenger was widely expected to reinforce Arsenal's defensive midfield in the summer transfer window, but the Gunners eventually failed to add a single outfield player to the signing of goalkeeper Petr Cech from Chelsea.
Now, with Arsenal lacking a natural replacement for Coquelin, that decision appears to have backfired. Wenger says he will attempt to address the situation in the transfer market, but Arsenal have eight games to get through until January, so how will they plug the gap? Here, we take a look at their options…
It rather summed up Arsenal's injury woes that Mikel Arteta, Coquelin's replacement at the Hawthorns, had to be taken off with a calf problem after just 35 minutes on the field. Wenger says the Spaniard is only a "short-term" absentee, but he has only made 14 Premier League appearances since the start of last season and his recent injury record does not inspire confidence.
Arteta remains an intelligent and reliable passer, but he has never been a natural fit for the role of defensive midfielder. He struggled against West Brom and scored an own goal, and he turns 34 in March. Injuries appear to have taken their toll, and he simply doesn't have the legs to cover the same amount of ground as Coquelin.
Arteta's replacement against West Brom was Mathieu Flamini. The Frenchman is a popular figure at the club and scored a memorable brace in a Capital One Cup tie with Tottenham earlier this season, but, like Arteta, he is entering the twilight of his career.
Flamini cannot match Coquelin's energy in front of the back four, and his weaknesses were exposed in Arsenal's 3-0 loss to Championship side Sheffield Wednesday last month. The 31-year-old offers experience and application, but he is limited in other regards.
One piece of good news to emerge from Wenger's press conference on Monday was that Aaron Ramsey has recovered from his hamstring injury. The Welshman has predominantly played on the right side of Arsenal's attack this season, but he is now a candidate to step into a more defensive role as cover for Coquelin.
Ramsey is one of the Premier League's fittest players, which gives him an immediate advantage on Arteta and Flamini, but his biggest strengths are going forward. His best performances have come when he is allowed to charge from box-to-box, and there are question marks over whether he could sacrifice his attacking instincts to play the holding role.
Wenger name dropped Calum Chambers when discussing how he could replace Coquelin. "We have other players who can play in this position, like Chambers, because he has been educated as a central midfielder," he said. "Sometimes this is a good opportunity for other players to turn up and show they can do the job."
Chambers has mostly been used at right-back and centre-back since his arrival from Southampton, but Wenger has always maintained that his future lies in midfield. Wenger might hope Chambers can make an Eric Dier-esque conversion, but he struggled badly in the position in a 2-0 defeat against his old side last season.