ON the plus side, Celtic managed to avoid injuries ahead of their vital Champions League play-off with Maribor but were unable to avoid some seriously wounded pride.
Ronny Deila rested all but one of the players who earned a first-leg draw in Slovenia on Wednesday but the club's first defeat in Inverness since the damning loss which cost Neil Lennon the title in May 2011 offered a damning verdict upon the reserves at the Norwegian's disposal.
This is still a formative period in Deila's tenure at Celtic but his team now trail the early leaders by four points after failing to score in a league match for the first time since December 2012.
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Deila handed starts at the back to Eoghan O'Connell - the cousin of British Lions rugby legend Paul - and Czech youngster Filip Twardzik, with Dylan McGeouch and Liam Henderson flanking Nir Bitton in a three-man midfield.
He may have been emboldened by the fact his predecessor had employed a similar tactic two years back, in the midst of qualifying ties against the Swedish side Helsingborgs, and still recorded a comfortable 4-2 victory,
Kris Commons recorded a clean sweep of Scotland's player of the year awards last season but his centrality to Deila's plans remains unclear. Omitted against Maribor, he started here in a centre forward role, perhaps the closest thing Scottish football has seen to a false No 9. Although he lasted the 90 minutes, it wasn't a huge success.
Despite all his tinkering, Deila never seemed happy with the combinations he had on the field and made numerous tactical switches during the match.
In the opening period the hosts wielded plenty of menace. Greg Tansey fired two long-range drives just wide, Marley Watkins was a menace on the right wing, while the excellent close control of Ryan Christie was very much to the fore. Celtic only looked the part in the second half of the first half. Dean Brill had to look lively to divert an Efe Ambrose effort over the bar after the Nigerian redirected a Henderson free-kick, then Commons - back in his conventional role off the front - helped set up Teemu Pukki, only to be defied by Brill's double save.
The English keeper also batted away a Commons drive and saw a sublime right-foot curler from Nir Bitton rebound off the underside of the bar. At the other end captain Charlie Mulgrew, the sole survivor from Maribor, cleared from under his own bar to defy Gary Warren's goalbound header.
The Norwegian wasn't satisfied. At half-time he replaced Twardzik with Stefan Johansen and put Callum McGregor on for Pukki.
The youngster, whose precious run of European away goals have taken the club to the brink of the Champions League group stages, added a spark to the proceedings. He might have had a penalty for a challenge from Danny Williams, although referee Bobby Madden was happiest when letting the game flow, but Celtic looked vulnerable at the other end.
Warren missed a golden chance from a set play before the goal arrived. Watkins was too quick and clever for his latest auxiliary opponent at left back, Johansen, and his cross was in the corridor of uncertainty between Lukasz Zaluska and Billy MacKay. The Pole could only palm the ball at the backtracking O'Connell, who had the misfortune to bundle the ball over his own line.
After Anthony Stokes replaced Leigh Griffiths, the Irishman set up Commons for Celtic's only real chance of the second half but he shot tamely at Brill. The home side were the more likely to add to their tally in the closing stages. From a sweeping counter attack, sub Nick Ross saw his effort pushed beyond the post.
Strangely, Inverness manager John Hughes felt his side had taken all the fortune going. He said: "I am an honest guy and we rode our luck. We have Dean Brill to thank for a few saves but to beat Celtic you need that luck."
In the Celtic corner, Ambrose admitted: "The manager should be angry. We never gave it our all. The last 20 minutes was not us. We just lost hope after conceding that goal.
"However, we are confident for Tuesday night. We know the importance of the game and know we will be at Celtic Park with all our fans. I don't think Maribor can stop us."