Costa was given his marching orders during Chelsea’s FA Cup quarter-final loss to the Toffees at Goodison Park and appeared to bite Gareth Barry’s neck before being sent off.
Goals from Romelu Lukaku and Barry secured victory for Roberto Martinez’s men and booked their place in the semi-finals of the FA Cup at Wembley.
And former Arsenal defender Keown admitted that he is surprised that Costa had not been sent off in England previously, claiming that the striker is good a disguising his offences during games.
Writing in his column for the Daily Mail, Keown said: “There’s no doubt Diego Costa is an exceptional talent but with him you have to accept all of the erratic behaviour that goes with his tremendous ability. You’re never going to have one without the other.
“With Costa, it’s all in — the good, the bad and the ugly. For him to be at his best as a player he has to get into this match mode where he is pest. We’ve seen when he’s not in that ‘Mr Nasty’ mode he isn’t nearly as effective.
“This is not to condone his behaviour, far from it. Costa plays on the limit and it’s almost impossible to believe this is the first time he has been sent off for Chelsea. He has faced retrospective bans but he’s actually very good at disguising his offences.
“Costa was lucky Barry didn’t pull away. If he had done, it would have been very easy to think there had been a bite. He was so aggressive with the way he went in with his head and he deserved to be sent off.”
Chelsea now only have positions in the Premier League to play for after they were dumped out of the Champions League and FA Cup in the space of a week.
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