You just know that Costa would have been right in the thick of the action had it happened before he was substituted.
But Costa was subbed in the 85th minute, following his Man of the Match display, for Nathaniel Chalobah.
The brawl started after Sergio Aguero’s horrendous challenge on David Luiz, which earned the City forward a straight red card.
There was plenty of pushing and shoving afterwards and referee Anthony Taylor then showed another red card to Fernandinho after he pushed Cesc Fabregas over the advertising hoardings. Replays have since shown, however, that the Brazilian midfielder was slapped by the Spaniard.
Video: Diego Costa's reaction to the brawl
It’ll come as no surprise to anybody that Costa desperately wanted to get involved - as this hilarious footage shows.
While the City and Chelsea players were involved in various heated exchanges, Costa ran off the bench towards the action.
Reaction on Twitter
Twitter reacts to Costa’s comical moment…
And there are loads of replies like this...
Costa was superb against City
Costa was magnificent for the Blues today. He opened the scoring in the 60th minute and then set up Willian 10 minutes later.
Eden Hazard then added gloss to the scoreline with a third goal in injury time.
According to Opta, Costa has now had a hand in 30 goals in 28 Premier League appearances (20 goals, 10 assists) since Boxing Day.
He’s back to his world-class best.
Is Diego Costa currently the best striker in the Premier League? Have your say by leaving a comment below.