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Sources have told ESPN that there are fears among Gunners' staff that Mari may have suffered ligament damage, casting major doubt over his future with his loan deal due to expire at the end of the month.
Arsenal paid a £4 million loan fee to acquire Mari from Flamengo in January and are thought to have an option to make the deal permanent for a further £8m.
Mari has made just three appearances for the club but when asked by ESPN whether Arteta still wanted the club to commit to signing Mari, he said: "Yes. This cannot be affected just because a player gets injured doing his job and defending our club."
Arsenal are weighing up similar decisions for several players with David Luiz out of contract at the end of the month, while Cedric Soares and Dani Ceballos due to return to Southampton and Real Madrid respectively.
With Luiz suspended, joining Mari, Sokratis Papastathopoulos (thigh) and Calum Chambers (knee) on the sidelines, Arteta is short of options at centre-back for Saturday's Premier League trip to Brighton.
Arsenal's £72m club-record signing Nicolas Pepe was an unused substitute at the Etihad Stadium with Arteta having said the winger needs to improve his overall form.
"It is clear that his consistency has not been at the level that he can produce. He is the first one to accept that, that's what I'm going to demand from a player of his level, calibre," Arteta said. "He has to be producing every three days at the level that he can be.
"He has to be a player that makes the difference, that is a threat, generates fear in the opponents and gives us a big threat in the final third and his work rate has to be related as well with that kind of performance. He knows that.
"He is such a nice kid, trying really hard and you have to respect the timing, the way he has adapted for the first year as well. A lot happened to him and we have to understand that and he is willing and I'm sure we are going to get the best out of him, I'm convinced of that."