Celtic manager Tony Mowbray claimed his side suffered again from midweek European exertions after being held to a remarkable 3-3 draw at Falkirk.
The length of the Clydesdale Bank Premier League separated both sides on the Parkhead side's return from Germany where they had drawn 0-0 with Hamburg in the Nordbank Arena on Thursday night.
However, the Bairns earned their point after coming from behind twice to level in the 83rd minute through substitute Mark Stewart.
Hoops' midfielder Aiden McGeady had a first-half penalty saved by Bairns' keeper Robert Olejnik before Gary Caldwell headed the visitors ahead just after the break.
That was the start of a goal avalanche which left supporters of both sides breathless by the final whistle.
Scott Arfield levelled from the spot after Caldwell had tripped Ryan Flynn, before Pedro Moutinho, re-signed by Falkirk following a spell at CS Maritimo, volleyed the home side ahead.
Parkhead substitute Scott McDonald, a 67th minute replacement for Paddy McCourt, headed the equaliser five minutes later before grabbing a second and at that point, it looked all over for Eddie May's side.
However, with seven minutes remaining, Stewart, on for Alex MacDonald, ran on to a clever pass by Flynn to slam the ball past the exposed Celtic keeper Lukasz Zaluska.
The Celtic boss put this latest blip down to an exacting trip to Hamburg.
“It was a tired performance from us,” he said.”It was probably as poor as we've been this season and the team didn't play well in the first half.
“It was the same defence which kept a clean sheet in Hamburg but mentally it was a tough day for the team.
“Generally, we have had mentally tired performances after games in Europe and I think that was one today. Yet, if we want to take a positive, the team tried to rally themselves from a losing position and showed great endeavour to get back into a winning position.
“They could have felt sorry for themselves, they had a tough week, getting back from Europe in the early hours (of Friday).
On McDonald, who was dropped from the side which drew in Hamburg, Mowbray said: “There is competition for places. “I’m delighted he scored a couple of goals.”