Ronny Deila has said that he is "very disappointed" with Celtic's 2-1 defeat to Aberdeen.
Celtic led after a Leigh Griffiths penalty, but second-half goals from Adam Rooney and Paul Quinn saw Aberdeen move top of the Scottish Premiership table.
Griffiths felt that Andrew Considine should have been sent off following the penalty incident.
"When you see it, Leigh is straight on to goal. But they had a man sent off and we had a chance to win the game or at least get one point and that is disappointing," Deila told Sky Sports News when asked about Griffith's claim.
"I am very disappointed with the result. We had control of the game until their penalty and I thought it was a very cheap one. It is a very easy penalty.
"But after the red card, I was very disappointed that we conceded a goal so easy on a set-piece."
Celtic's attentions will now turn towards their Europa League fixture against Ajax on Thursday.
