The Blues striker finds himself fighting for a league and cup double since his controversial offer from China in January, but has he got worse since?
ANALYSIS
Diego Costa is regarded as one of Chelsea's most important players and remains their leading scorer this season, but stats from Opta show that his form has taken a dip since his offer from Chinese Super League club Tianjin Quanjian in January.
The Spain international ultimately chose to decline the offer and remain at Chelsea to compete for the Premier League title and FA Cup glory, but he was offered a staggering £30 million-per-year contract, which would have almost tripled his salary and may have proved to be a distraction.