Carlo Ancelotti admits David Luiz must learn to calm down after narrowly escaping being sent off in Chelsea's win against Manchester United.
The new £25million signing was lucky to avoid a second yellow card for a cynical foul on Wayne Rooney
during Tuesday night's controversial game at Stamford Bridge.
The 23-year-old's aggressive approach marred what was otherwise another virtuoso display from the Brazil defender, who had scored a stunning equaliser minutes earlier.
Manager Ancelotti acknowledges Luiz needs to improve his discipline if he is to remain an asset and not a liability.
"He has to know English football," Ancelotti said. "He has to be more calm on the pitch. Obviously, he's showed fantastic ability and quality.
"He has to improve, but he will because he'll have more experience and knowledge about English football. He can change his behaviour on the pitch."