Arsenal might need to change their transfer plans after another injury blow.
Mikel Arteta showed faith in David Luiz towards the end of last season as he was handed a contract extension, but he is now likely to miss the start of the new season.
Steve Bruce looked all set to add Rob Holding to his playing squad on a temporary basis, but Arteta might be forced to keep him at the club following the recent update.
The Athletic have reported that Luiz could be out for up to six weeks depending on how he responds to treatment.
They add that although Holding was on course to join Newcastle, Arsenal delayed that move and he could now be in the starting XI to take on Fulham on Sunday.
The Gunners have been able to add both Gabriel and William Saliba to their playing squad ahead of the new season, with the futures of Sokratis Papastathopoulos and Shkodran Mustafi uncertain.
Former Chelsea defender Luiz came under fire after a series of mistakes in the Premier League last season, but he bounced back to help them win the FA Cup.
Arteta said in July after the semi-final win over Manchester City: "This is part of football, you can go down but I didn't have any doubts about David's reaction.
"He held his hands up after that [City] game and he didn't have to do that because we all make mistakes.
“The way he has been training and helping others has been phenomenal and I am delighted that people can now see this side of him as well and praise him because he deserves it.
"He has won everything in different countries so he brings that [experience] with him.
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“Not only that but I want him to perform on the pitch and he is doing that again in a really good way and I'm really happy for him today.
"David doesn't need a lot of management. What he needs is that we trust him and we don't doubt what he can do.
"The best way to do that is to make him play.
“He can say that throughout his career he has had some difficult moments and some incredible moments, but big athletes go through those moments and I'm happy that he's at the level he's playing now."