Arsenal already have a defensive crisis before the season’s even started

This really isn't what Arsenal fans wanted to hear.

Arsenal are stateside for their preseason tour of the USA. The Gunners have named their squad for their preseason friendlies against the MLS All-Stars and Liga MX side C.D. Guadalajara later this week and there was a notable absentee. In fact, Per Mertesacker's omission was so notable that the club sent out a separate update explaining that the BFG was not brought to the States because of a knee injury. https://twitter.com/Arsenal/status/757564934310035458?ref_src=twsrc%5Etfw Arsenal didn't provide any further information on the knock, but reports in Spain make for very grim reading for Gooners. El Confidential journalist Kike Marin, who broke the news of Arsenal’s move for Alexis Sanchez in 2014, claims that Mertesacker could be out until around Christmas. If the reports are true, it could mean a massive blow for Arsene Wenger as his options in defence were already set to be limited at the start of the season. https://twitter.com/Kike_Marin_/status/757629633550487552?ref_src=twsrc%5Etfw Laurent Koscielny is set to miss the beginning of the season after he was given an extended break after Euro 2016, while Gabriel has not travelled to the USA because he is suffering from tonsilitis. This means that as it stands, Arsenal are down to 20-year-old new boy Rob Holding and 21-year-old Calum Chambers as their only alternatives in the middle of defence. Left-back Nacho Monreal has played centre back for Arsenal in the past also, so he could play a more central role.