The really serious test of how the Arsenal defence is going to be able to cope with the absence of our Wprld Cup winning Germany international Shkodran Mustafi is not likely to come until the Premier League game away to the current leaders Manchester City on November 5th.
Even without their star striker and top scorer Sergio Aguero, who is reportedly going to still be out with his own injury problem when Arsenal go to the Etihad stadium, City have looked deadly in attack and will be extremely hard to stop from scoring.
Arsene Wenger will almost certainly want to play three at the back for that game as in theory it makes a team more defensive, and so the boss may also want to stick with that formation for the games, especially the Premier League ties, that come before that tough away fixture in order to get the players as used to their roles as possible.
However, there is certainly an argument for the Gunners reverting to a back four to deal with the absence of Mustafi. We hacve two very good full backs in Bellerin and Monreal, and we could even use the Spaniard as one of two centre backs with Kolasinac at full back.
We have ther tried and tested pairing of Koscielny and Mertesacker, with Holding and Chambers as back up and playing that system does give a bit more attacking focus and with Watford, Everton and Swansea to come, maybe that would be just what the doctor ordered.
What do you reckon Gooners?