It will have been a difficult decision for Arsene Wenger to make as he got the Arsenal squad ready for this Premier League away game against Chelsea, because after a slow start to the season we really cannot afford to take nothing back with us from Stamford Bridge today, but at the same time our best player Alexis Sanchez was not match fit.
The Chilean needed some game time to gain fitness and match sharpness so the boss started him against Cologne but because of the way the Europa League match went he could not afford to take him off. Fortunately Thursday night did see Alexis sharpen up and find his form over the space of an hour or so, but even with his powers of recovery it would be a risk to start him just two and a bit days later.
I expect Sanchez to be on the bench and to come on at some point, but Wenger will go for the players who are fresh and having left Danny Welbeck, Mesut Ozil and Lacazette out of the Europa League clash it will be these who start today. Ramsey and Xhaka will be back in the middle with Bellerin and Kolasinac as the wing backs and we will still have a back three but it will look a bit different, with Koscielny on the left instead of Monreal and with Mustafi on the right with the big German Mertesacker in the middle.