The London derby today may well have been one of the biggest matches we will see this season, despite being in the middle of September. Wenger and Mourinho going head to head is always quite a spectacle, but this fixture was packed with as much drama as ever and Diego Costa was – of course – in the middle of it all.

Chelsea provided a performance that was glossed in a Mourinho bitterness and a competitive edge that bordered on poor sportsmanship, with two red cards for Arsenal ultimately ruining any faint chance they may once have had.

Here are three things we learned from today's game:

Oscar is still so crucial

Chelsea v Queens Park Rangers - Barclays Premier League

His return from injury has coincided with Chelsea’s return to winning ways in Europe and England yet Oscar is still one of the most under rated players in the league.

The Brazilian’s high pressing game is crucial to Chelsea when in full flow and his tenacious approach is vital in helping out his other midfielders, whilst the goal threat is crucial in support Diego Costa’s efforts.

Diego Costa is the games best wind up merchant

costahazard

Gabriel Paulista was the latest to fall into the Diego Costa mind games and Costa, who clearly has no concern for his own reputation, made the Brazilian centre-back look foolish.

He’s childish, petty and bad tempered, but Costa’s antics have regularly been beneficial for Chelsea. Costa was lucky to stay on the pitch today, but his questionable approach won Chelsea the game and it is incredible how defenders continue to get suckered into it.

Ramsey must be in central midfield

Aaron Ramsey

Aaron Ramsey is one of the best young central midfielders in world football, yet he cannot get in the Arsenal team in the middle. As talented as Santi Cazorla is, Ramsey’s engine and box to box influence is missed alongside Coquelin and having a central midfielder on the right hand side can leave the team lacking balance.

The Welshman would have given extra stability in the middle against Fabregas and Oscar and perhaps it would’ve been best to maximise the pace in the side by playing Chamberlain wide right.