Already in the stocks due to his X-rated lunge on Xabi Alonso in the World Cup final, De Jong was heavily condemned his tackle on Ben Arfa at Eastlands in October, even though it went unpunished by referee Martin Atkinson, who chose not to have the matter investigated again by the Football Association either.
Ahead of the Boxing Day rematch with the Magpies at St James' Park, Mancini maintains De Jong was innocent of any crime and remains a key figure in his side's quest for silverware.
Bad break: This challenge from Nigel De Jong (right) left Newcastle's Hatem Ben Arfa with a broken leg
Foot up: Holland's Nigel de Jong does THAT challenge on Spain's Xabi Alonso during the World Cup Final
'I am sorry for what happened with Ben Arfa but this can happen in a football match,' said the City boss.
'It has not affected Nigel and I never thought about leaving him out. There are a lot of players in the world who attack the ball like Nigel. In this instance he was very unlucky.But he is a fantastic player and very important for us.
'He is the only player we have got with his characteristics. He always stays in front of the defence, so he helps the defenders. But he helps the strikers and wingers too.'
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