United's second successive European defeat did not befit their manager's 200th game in elite European competition and it bore out why City, stung by the desultory manner of their own disappearance from the continental stage, dare believe their strike-force will cause United big trouble in three days' time at the Etihad.
Ferguson began the game from the relative warmth of the stand but even from that distance, his defence looked discomfiting.
The game's only significance was the opportunity it offered to restore Wayne Rooney's (pictured left) match fitness and United's rearguard some credibility before Sunday. Rooney looked enterprising in bursts but the defence didn't.
A "cartoon cavalcade" is how the manager described the unit which conceded three goals at Reading last weekend, and the title of that 1970s Scottish TV show summed up the first half, at least. An early loose pass back into the area from Ryan Giggs had Chris Smalling flapping into a hasty clearance straight to Rui Pedro, whose shot was expelled by David de Gea's outstretched knee. This was not exactly encouraging -- and some similar faffing from Rooney, sending the ball back between De Gea and Phil Jones, was little more appreciated.
It is the high opposition ball into the area which is troubling United, though, and which will exercise the manager's mind in his quieter moments between now and the Etihad trip. Smalling was exposed by it when Vincent Kompany scored the deeply significant winner in last April's derby and twice from first-half corners Cluj were granted free headers when there should have been aerial challenges.
This was not a good night for Tom Cleverley, who was substituted for Paul Scholes and marched straight towards the dressing room just before the break, suffering from a calf injury. He is a doubt for Sunday, Ferguson said. Giggs lacked his customary light touch, too, in what has not yet been a commanding season for him.
Only as half-time loomed did United begin to threaten. Rooney was generally withdrawn, playing wide on the right. His clipped effort - the first half's only object of beauty - was flipped over the bar by impressive Cluj goalkeeper Mario Felguerias. But the uncertainties and lack of a collective spirit were persistent in United's defence.
Ferguson has said in the past week that he is not happy flipping his goalkeepers and a commanding stopper really does seem to be required. There was simply no defence available to atone for Scholes' errors in the 55th minute which allowed the Romanian side to secure a lead.
First, Scholes' loose pass caught out an unfortunate Nick Powell; then Luis Alberto capitalised -- racing past Scholes to fire a 30-yard shot into De Gea's top left-hand corner. The goalkeeper had no chance, though neither did he demand that his defence press and close down the midfielder as he slipped past Scholes.
United did not look like launching a comeback. Their football lacked tempo and urgency, as throughout the campaign. The final ball was always lacking.
This bodes ill for the knockout phase, as much as for Sunday.
The derby match will bring different personnel and a different challenge, Ferguson insisted.
"It will be a different kettle of fish," he declared. "The experienced players who have been playing have got to get their act together. It's as simple as that."