And now Chelsea. Usually Conte's 4-1-4-1 has Oscar in the middle next to Matic, and his job is to link the midfield with the striker during attacks. This formation looks more like Chelsea are going to sit deep and try to hit Arsenal on the counter-attack - Fabregas' start in midfield certainly makes this seem far more likely, as his long balls over the top for Costa are a straight forward solution to the pressure Arsenal will look to put on them in the defensive third.

Willian and Hazard will probably play quite high up the pitch, making this formation look like a 4-3-3 in attack and a 4-1-4-1 in defence. The attacking version of this system looks like a 4-1-2-3 in attack.

4:40pm
The Arsenal team

Either Wenger doesn't think Perez is good enough to lead the line, reckons Giroud simply isn't fit enough to start, or he thinks his team needs some fluid rotation upfront to open up the Chelsea defence. Sanchez isn't great as a striker, though he has performed well in that position for his country. Most of the noise from Arsenal fans on Twitter is of disbelief that Wenger hasn't started Xhaka.

That's just Twitter though, I really wouldn't give it too much thought. It's mostly teenagers and the kinds of people you'd ignore in a pub.

4:33pm
Team news
Arsenal start without a striker... while Chelsea have Fabregas in the team, just like we (me) predicted!

Arsenal

Cech; Monreal, Mustafi, Koscielny, Bellerin; Cazorla, Coquelin, Walcott, Ozil, Iwobi; Sanchez

Subs: Ospina, Holding, Gibbs, Xhaka, Oxlade-Chamberlain, Lucas, Giroud

Chelsea

Courtois; Ivanovic (c), Cahill, David Luiz, Azpilicueta; Kante; Willian, Fabregas, Matic, Hazard; Diego Costa

Subs: Begovic, Marcos Alonso, Chalobah, Oscar, Moses, Pedro, Batshuayi.