Arsene Wenger says he will look into the cause of a large number of Arsenal first-team players being struck down by injury.
Ahead of Sunday's north London derby against Tottenham, and a crucial run of fixtures afterwards, Arsenal are currently without the services of Mesut Ozil (hamstring), Aaron Ramsey (thigh), Theo Walcott (knee) and Jack Wilshere (foot).
Walcott is ruled out for the rest of the season, while Wilshere is unlikely to return until the campaign's final stages.
Arsenal trail Chelsea at the top of the Premier League table by seven points going into the weekend and will face the table-toppers as well as title rivals Manchester City before the end of March.
And with Wenger missing so many key players at a possibly make-or-break stage of the season, the Frenchman will do everything in his power to get to the root of the problem.
"I am concerned that this happens," said Wenger.
"If you look at our overall injury list going into such a decisive part of the season, we have not Wilshere, not Walcott, not Ozil, not Ramsey and we went to Bayern without (Kieran) Gibbs and (Nacho) Monreal.
"We are analysing very deeply why it happened and to see if there is a link between all these injuries.
"For Walcott it's completely bad luck. Wilshere – I don't think it is linked with the other injuries, it's more linked with his history and the kick he got.
"But the rest, maybe we have to find why it happened.
"It's very difficult to find any obvious reason why. For example, a player like Ozil – he was rested against Stoke, then he goes to Germany and he trains different, sometimes on a different ground with different sessions.
"He played the whole game (against Chile) and the whole game for us against Everton and he produced on that day, doing more physically than usually and he paid for it the next day. Why? I don't know."