Well, that got bad fast. Olivier Giroud suffered a seemingly innocuous knock at the end of the Everton game, and there were concerns that he could miss a few weeks. Now, reports from Matt Law in the Telegraph and L'Equipe's Bruno Constant say the injury is worse than originally thought. Law reports a possible broken ankle with Constant saying it's a break in the foot, but either way, this would be bad news for Arsenal.
Other in-house options at striker range from the young (Yaya Sanogo) to the out-of-position (Alexis Sanchez) to the young and out of position (Joel Campbell). It's certainly not an ideal situation, and if additions can be made at the position, one would think Arsene Wenger would look to move quickly before the transfer window closes.
Options mooted by Matt Law include the oft-rumored Loic Remy, free agent Samuel Eto'o, and out-of-favor Danny Welbeck. Less likely would be Falcao or Edinson Cavani, but if Wenger can convince Monaco or Paris Saint-Germain to sell, certainly the gap left by Giroud's injury would be considered filled. Neither of those moves would be likely unless Arsenal can get past Besiktas on Wednesday and move into the Champions League group stages.
There's exactly a week until the transfer window closes, so I'd imagine Wenger, Dick Law, and Ivan Gazidis won't be sleeping a lot for the next seven days.