Diego Costa's involvement in Gabriel's sending off was one of the major talking points of Arsenal's 2-0 defeat at Stamford Bridge.
Whereas Arsene Wenger complained about the Chelsea forward's "unacceptable behaviour", the following footage might explain some of the bad blood between Costa and Arsenal man.
The video shows a clash from the 2013/14 La Liga season. Diego Costa was leading Atletico Madrid to La Liga victory that season, and came up against a Villareal side which featured Gabriel.
When Costa is seen brushing against Gabriel with his elbow, the defender throws himself to the floor with a pathetic dive.
It's no wonder Costa held a grudge.
https://www.youtube.com/watch?v=dEpj1upGRq0
