Arsene Wenger has been handed an unwelcome yet familiar dilemma as they prepare for the new season.
Thomas Vermaelen is already out injured and unlikely to be fit until September with a back injury his ailment, and now Laurent Koscielny has gone down too.
The Frenchman suffered an ankle injury in training and is unlikely to be risked against Nagoya Grampus 8 in their next friendly match.
It leaves Arsenal with just Per Mertesacker and youngster Ignasi Miquel as options, along with the possibility of Bacary Sagna playing as centre-back.
One option certainly off the table is the recall of defender Johan Djourou, who is suffering his own problems.
The out of favour Swiss defender was loaned out to Hamburg for the season, and has had a nightmare start.
He went off injured just four minutes into his debut two weeks ago with a muscle problem and is still struggling to get fit.
German newspaper Bild reports that Djourou has undergone 'minor surgery' on his groin complaint and will miss the start of the Bundesliga season.
It's a big setback for the player after a stop-start couple of seasons, but he will hope to be back in action as soon as possible.
Whether Arsenal would have considered bringing him back in an emergency is doubtful, but the option now appears to be a total non-starter.
Koscielny is likely to be fit for the season kick-off, but the situation with Vermaelen already out displays how precariously Arsenal's resources are balanced in the position.
It would make sense for the club to dip into the transfer market and bring a central defender in as cover, with Ashley Williams a much rumoured target.
With time running out until the season begins, now is the time to get working on such a back-up plan.
Do you expect Arsenal to sign a central defender? Who?
image: © Ronnie Macdonald