It's a strange business to be afflicted with home sickness but to have your health restored with a road trip or by a visitor from foreign parts, but that's the way it is for Celtic.
The latest embarrassment on their own ground was inflicted by tiny Arbroath, who managed to score both goals – first from Alex Keddie into his own net and then the equaliser from Steven Doris' late deflected free-kick – in this fourth-round tie.
Celtic should, given their form in Champions League ties, be able to take care of Spartak when the Muscovites arrive in the east end of Glasgow for their final group stage fixture on Wednesday night. It does seem that Neil Lennon's players are galvanised by the electricity of capacity partisan crowds – witness their performances against Barcelona and Spartak or at the likes of Pittodrie and Tynecastle, the locations of their most recent wins.
The problem which increasingly gnaws at Lennon is how to generate a reliably powerful current. The nearest Celtic have come to consistency in all competitions was when they ran up six successive victories in a month, but that sequence ended on October 20.
Since then, their form has been spottier than a youth team player's face, with only four wins from 10 outings and none at home since they mugged Barca back on November 7. Between times Kilmarnock, St Johnstone, Caley Thistle and Arbroath have departed with wins or draws while the Hoops have slunk from the field with the jeers of the natives echoing in their ears.
There is an assumption that at some stage, probably soon, Celtic will simply cut loose and assert their domination on the domestic competitions. That, though, hasn't subdued dissatisfaction with the current inability to render decisive performances and victories where it matters most.
Meanwhile, Celtic accommodate the replay at Gayfield on Wednesday week, a fixture that will replace the originally scheduled home league encounter against Dundee United.
There could not be a greater contrast in football than that between the Camp Nou and Arbroath's home ground on the verge of the North Sea, which is known to combine with easterly gales to toss driftwood into the premises.
When it was suggested to Derek Holmes that Celtic would not fancy a midweek engagement at Gayfield in midwinter, the Arbroath forward replied: "I don't enjoy a night out in Arbroath! The wind will be out."
Both sides agreed – Arbroath reluctantly – that the most memorable occurrence of the day was Keddie's own goal, not that the defender was in any way culpable when an attempted clearance by his fellow central defender Stewart Malcolm rebounded from his posterior into the net.
"The ball was actually over the line but big Stewart Malcolm had a panic and tried to clear it across the goal," was Keddie's version. "I tried to get out the road, but it smacked off my bum and went into the bottom corner."
(© Daily Telegraph, London)