Arsenal manager Mikel Arteta has revealed that William Saliba is out of Sunday's Premier League clash with West Ham United and may take "a few weeks" to get back up to full fitness.
The France international has sat out the Gunners' last three Premier League matches since sustaining a back injury in their Europa League last-16 second leg defeat to Sporting Lisbon.
Arteta has been coy to put a timeframe on Saliba's recovery, but he hinted last week that one of the centre-back or Eddie Nketiah could have been back in the squad against Liverpool.
Neither man was able to force their way back in for that 2-2 draw, although Nketiah has been seen on the training pitches as he closes in on a return from an ankle injury.
Addressing the media at Friday's pre-match press conference, Arteta revealed that Nketiah was available for selection again, but he would not be able to count on Saliba for the London derby.
With clashes against Chelsea, Newcastle United and Manchester City to come, Arsenal will be desperate to have Saliba back in the fold for the run-in, but Arteta has suggested that the 22-year-old may not be available for quite a while yet.
"William [Saliba] is still not available. He's progressing well and we are hopeful we'll have him available in the next few weeks, but we'll have to see, arsenal.com quotes Arteta as saying.
"He's not far from starting to do that. Obviously we need to be cautious because of the injury, but he's evolving well. Eddie is back and fully fit now."
Saliba's absence should guarantee a fourth successive Premier League start for Rob Holding, whose only top-flight goal to date came in last season's 2-1 win over West Ham at the London Stadium.
Knee surgery victims Takehiro Tomiyasu and Mohamed Elneny are also sidelined for the Gunners, whose lead at the top of the Premier League table was cut down to six points with their stalemate at Anfield.
Manchester City - who still have a game in hand - will close the gap to three points if they beat Leicester City on Saturday, and Arteta is taking nothing for granted against his former manager David Moyes, who he would "run through a brick wall for" at Everton.
"I know David really well and how he's going to prepare for the game as well, and we are ready. It's going to be a fight; it's going to be another big derby for us and we're going to be at our best to win it," Arteta added.
"More than respect, I think it's admiration. I loved playing under him, I would go through a brick wall for him when he was my manager, as everybody would in that squad.
"[He's] a really good coach, exceptional at managing the group and dealing with individuals, and he's a very special person, very trustworthy, and a man who honours his word. He always did it and he's someone I learnt a lot from."
Arsenal sit 13 places and 43 points better off than relegation-threatened West Ham, who enter the derby on the back of a 1-1 draw with Gent in the first leg of their Europa Conference League quarter-final.
The Hammers only have one confirmed injury absentee for Sunday's game in the shape of Gianluca Scamacca, who is now confirmed to be undergoing surgery on a knee problem.
