The Bhoys have suffered a tough December so far, with defeats in the Scottish Premiership against Kilmarnock and Hearts blowing the title race wide open.
Rodgers’ side have appeared a shadow of the Celtic team under Ange Postecoglou last term and questions are beginning to be asked by the fans.
Rangers can move to within two points of Celtic if they beat St Johnstone at Ibrox on Wednesday evening, something which would further deepen woes.
Celtic legend Hartson has pondered what is going wrong and Parkhead and sees two possible answers, neither of which involve the manager.
The former striker wrote on X: “2 things possibly going wrong at Celtic.
“The players are coasting and some of them think they are better than what they are.
“Secondly the players are not putting everything in for the manager.”
Celtic are likely to back Rodgers in the transfer market when the January window opens, but they are due to play host to Rangers before the new year in what could be a crucial game in deciding the destination of the title.
