The Spaniard was heavily involved in the game’s most controversial incident late in the first-half as he clashed with Gunners defenders Laurent Koscielny and Gabriel Paulista.
Costa was fortunate not to be shown a straight red card after he raised his hands into the face of the Frenchman and then played a huge role in Gabriel getting sent off as he reacted to what appeared to be a flick from the Brazilian.
The Blues went on to take full advantage of the numerical advantage as Kurt Zouma broke the deadlock early in the second half after heading home Cesc Fabregas’s free-kick and then Eden Hazard’s deflected effort in injury time sealed all three points for the hosts and made it back-to-back victories in the week.
Chelsea 2-0 Arsenal: Player Ratings as Kurt Zouma impresses and Mesut Ozil vanishes
Jose Mourinho: Eden Hazard is the best player in the Premier League
Chelsea: Jose Mourinho refuses to criticise underperforming star man, although stats suggest a decline
Take a look at the reaction to Costa’s antics from a selection of supporters on Twitter:
To be clear, there’s a huge difference between ‘being successful winding people up’ and ‘getting away with cheating.’ #Costa
— FG (@FunnyGooner) September 19, 2015
Can’t get over how Dean didn’t send off Costa. The only possible explanation is match fixing. — The Twelfth Man (@_The12thMan) September 19, 2015
Football isn’t football wen u have ppl like Costa playing it. That guy has no place in a sport field.
— Harish (@harishAFC) September 19, 2015
I Pity D. Costa, the Ripple effect of his Act today would be Epic. Coaches, Defenders, Refrees & Fans Would all come At him. Mark my words — Charles Enwere (@CharlesEnwere) September 19, 2015
This is soo frustrating. Its like standing up to a bully who harasses people and later its u who gets punished ! #Costa
— Römeo (@Arsenal490304) September 19, 2015
Costa is the biggest disgrace I have ever witnessed
— Neilby_Gooner 70 ? (@Neilby70) September 19, 2015
Today’s a shame not just because it was unfair but because it was a really even, interesting match until Costa and officials ruined it — Sam Drew (@samueljadrew) September 19, 2015