Arsenal boss Mikel Arteta has confirmed that Declan Rice and Cristhian Mosquera will undergo further tests to learn the extent of the injury they sustained against Brentford on Wednesday.
The Gunners maintained their five-point lead at the top of the Premier League table with a 2-0 win against Brentford at the Emirates, but the team suffered further injury problems.
Rice appeared to point towards his calf before he was brought off late on, while defender Mosquera was substituted in the first half with what could be a knee issue.
Speaking to reporters after the match, Arteta revealed that further tests will take place on Thursday, saying: "Obviously it's never good news. Declan had to come off, we don't know. We have to see tomorrow what he's got.
"Mosquera is the other one that is out. Obviously we have Gabriel and [Saliba] out as well. So we have to adapt.
“We have to wait and see [with Mosquera]. It's probably part of the knee or ankle, we don't know."
The Gunners will play Aston Villa on Saturday at 12:30pm, and it would be surprising if either player was ready for that match.
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Declan Rice injury: How long could midfielder be out for?
If Rice has sustained a calf problem, then fans will hope that the Englishman has not suffered a Grade 3 injury, which could see him sidelined for up to three months.
Given Arteta confirmed that the 26-year-old was able to walk after the game, perhaps he has picked up a Grade 1 or Grade 2 injury.
A Grade 2 issue would mean that Rice would miss anywhere from three to six weeks of action, while a Grade 1 might involve as little as a week on the treatment table.
If Rice was to miss just a week of football, the only two games he would be unavailable for would be Aston Villa on Saturday, and Club Brugge in the Champions League on December 10.
Cristhian Mosquera injury: Who will start against Aston Villa?
Arsenal were already suffering from an injury crisis in the backline, with William Saliba and Gabriel Magalhaes both absent against Brentford.
The former could return in the coming days, though it may be risky to throw him straight back in against Villa, while the latter may not return until sometime in January due to a groin issue.
If Arteta decides to protect the fitness of Saliba, perhaps Jurrien Timber will be selected alongside centre-back Piero Hincapie, especially as he was brought on as a replacement for Mosquera.
Both Ben White and Riccardo Calafiori are capable of playing in central defence, so while Arsenal's options are stretched thin, they do have experienced players in the squad that could fill in.