Leaden, stale, disheartening - where do Celtic & O'Neill go from here?

To Celtic fans it might seem like sacrilege to doubt Martin O'Neill's capacity to get them through whatever it is they're going through right now - a slump or something deeper - but keeping the faith is surely becoming testing.

After their shellacking at Ibrox on Sunday, Celtic's response against Ferencvaros was another heavy defeat and three more goals conceded.

More absent-minded stuff in the midfield, more loose defending, more negativity and lack of accuracy on the ball, no great grasp of the basics of pass and move, not enough intensity, not enough work-rate, not enough of anything that you need to give yourself a chance.

At times, as it meandered along at 3-1 to Ferencvaros, Celtic tried to stage some kind of gallop but their attempts were from distance, hopeful efforts rather than anything built on the back of coherence and pressing and speed.

Celtic at their best - in the finest days under Ange Postecoglou - were all about aggression and ingenuity, about dynamism and risk-taking, about pace and belief and pulling defenders into places where they did not want to be.

Celtic are 'little bit broken' - but is change of shape 'worth risking'?

The second act of this season's Old Firm show on Sunday is still a hard one to call, partly because it's at Celtic Park and also because there surely has to be some kind of response from O'Neill's team to their pitiful fate at Ibrox last weekend.

Their fans will be worried, though. Five goals given up against LASK, a desperate experience at Ibrox - and now this.