Ben White is set to miss Arsenal's Premier League game away to Manchester City next weekend after testing positive for Covid.
The defender was ruled out of the Gunners' defeat to Chelsea on Sunday after he became their latest player to test positive for the virus.
Pierre-Emerick Aubameyang, Alexandre Lacazette, Willian and Runar Alex Runarsson were forced to miss Arsenal's loss at Brentford last weekend after also contracting Covid.
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Speaking after Chelsea beat his side 2-0 at the Emirates, Arsenal manager Mikel Arteta said nine first-team players have been affected by Covid since the start of the season, adding: "It's really challenging. The majority are big, senior players.
"We put out there a team that would probably be unprecedented in the history of this football club. But credit to the boys, how they're trying, the passion they are trying to bring to the team.
"They are playing with a lot of courage. They are trying their best. At the moment it is not enough to win football matches.
Asked if White - who joined the club from Brighton for £50m this summer - would be available to return for the trip to City next Saturday, Arteta said: "I don't think so, no."
Aubameyang made his comeback in the derby defeat to Chelsea after coming on as a second-half substitute, but Arteta said his captain had to battle to even make the bench after "really struggling" with Covid.
"Auba made a real effort to be able to be on the bench today," he said. "He only trained one day. He really struggled with the illness and he was in bed for a long, long time.
"He wanted to be in the squad, he wanted to try to help the team and I thought that he did help the team when he came on."
Speaking after the defeat at Brentford, Arteta said he was "surprised" the fixture was not postponed following the outbreak in his squad.
There is no official threshold for the number of positive cases that would cause a game to be called off, but the 2021/22 Premier League handbook states "permission will not be granted to postpone a league match where the applicant club has 14 or more players listed on its squad list available".
Arteta refused to comment on claims that his players contracted the virus during a party for Aubameyang's son, saying: "I don't know where it came from. We can only guess where it came from.
"A week before they had three or four negatives and then a positive. We have no clue where it came from."
By Sky Sports' Gerard Brand
Club-record signing Romelu Lukaku scored and put in a dominant display on his second Chelsea debut as they beat Arsenal 2-0 at the Emirates on Super Sunday.
Nearly 10 years after his first debut, £97.5m summer signing Lukaku registered his first goal for the club, tapping home at close range from Reece James' ball across the face of goal (15) after the Belgian's superb hold-up play had triggered the move.
James doubled Chelsea's lead with a clinical finish from the right side of the box with Arsenal too engrossed in Lukaku again (35), before the hosts had a strong penalty call denied by both Paul Tierney and VAR as Bukayo Saka went down under James' challenge.
Lukaku was denied a second by Bernd Leno's brilliant reflex save onto the crossbar from a header late on - Sky Sports' Gary Neville described his performance as "the complete centre-forward display" - and while Arsenal showed brief glimpses, Chelsea's victory was overall comfortable and classy.
It doesn't get any easier for Mikel Arteta and Arsenal, whose reshuffled back four struggled desperately with Lukaku and Co; they sit 19th and travel to champions Manchester City after the Carabao Cup tie at West Brom on Wednesday, live on Sky Sports Football.
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