Arsenal have confirmed that defender Gabriel was not included in the Gunners' squad to face Chelsea as he is self-isolating after coming in 'close contact' with the coronavirus, while David Luiz and Willian have missed out through an unrelated illness.
The trio were left out of Mikel Arteta's matchday squad for the all-London clash, with Pablo Mari, Gabriel Martinelli and Emile Smith-Rowe being called up to make rare starts against the Blues on Boxing Day.
And the club confirmed that Luiz and Willian were excluded from the squad after feeling unwell and will now be monitored closely, while Gabriel is in self-isolation having come in close contact with a carrier of the virus.
Gabriel will now miss Arsenal's next three matches, meaning he won't feature against Brighton & Hove Albion or West Bromwich Albion, while Luiz and Willian may face similar fates.
The duo will be tested again before the next set of fixtures, but their illness prevented them from partaking against the Blues.
This means that the former Chelsea pair were not able to line up against their former side at the Emirates, as Arteta opted for youth in the form of Smith-Rowe and Martinelli in attack, while Mari returned to the backline alongside Rob Holding and Kieran Tierney.
Martinelli also played his part in Arsenal's 4-1 defeat to Manchester City in the Carabao Cup in midweek, and Smith-Rowe impressed in his brief cameo off the substitute's bench. Arteta will be hopeful that Luiz and Willian produce negative test results and return to action soon, as he needs as many available players at his disposal as possible heading into the busy winter schedule.