Chelsea striker Diego Costa is renowned for his fiery temper on the pitch - but off it, by all accounts, the Brazil-born Spain international is a perfectly amiable chap.
However, new footage has emerged showing Costa in an altercation with the person next to him in the crowd at Stamford Bridge during the recent 1-0 victory over Manchester United. (You can see the clip by scrolling down this page).
It's safe to say, though, that Costa was only joking - and his reaction was, in fact, a funny response to his manager Jose Mourinho attempting to rouse his players the club's supporters.
The 26-year-old missed the win over the Red Devils because of a hamstring injury but should be back for this weekend's Premier League clash against Arsenal at the Emirates Stadium.
Costa still has an excellent chance of finishing the season as the Premier League's top scorer - he currently finds himself a goal behind Manchester City's Sergio Aguero and Tottenham's Harry Kane - and will have played an instrumental role in helping Chelsea win the title for the first time since 2010.
Temperament is still a big problem
But, as he did during his Atletico Madrid days, Costa has struggled with his suspect temperament at times this season.
The striker has somehow managed to avoid a red card since joining from Atletico last summer but was handed a three-match ban for stamping on Liverpool's Emre Can during a Capital One Cup semi-final clash against Liverpool in January.
In almost every match this season he has been involved in some sort of spat with an opponent - and it's important that he curbs his temper to avoid costing Chelsea in the future.
Costa disappointed in Champions League
Furthermore, while Costa has undoubtedly been prolific in the Premier League this term, his goalscoring exploits in the Champions League left a lot to be desired.
Chelsea's first-choice centre-forward failed to score a single goal in his seven Champions League appearances this season and was ineffective in the decisive quarter-final second leg tie against Paris Saint-Germain last month.
Chelsea fans: do you trust Diego Costa to perform - and keep his head - in the big matches? Have your say in the comments below!