UNITED just can't help themselves as once again they managed to squeeze more drama out of a European group that should have been over a month ago.
Publicly, Sir Alex Ferguson laughs it off as an endearing trait.
Privately, he must be sick to death of it. How he is still managing to cope with it with his 65th birthday coming up on New Year's Eve heaven only knows.
Twelve months ago in Lisbon the Reds threw away an early advantage to shatter their Euro dreams and last night they generously allowed the Portuguese side a goal start.
This so-called charming peculiarity has become wearing and might once again be their comeuppance in the knockout stages when Europe's elite are pitched into the last 16. It is hard to imagine a Barcelona or Milan passing up a goal start.
If they could just get this irritating characteristic out of the system once and for all then the knockout rounds might just be a shade more trouble-free for the Group F winners.
The wounds from Lisbon last December are still so raw that a strangling tension gripped Old Trafford both on and off the field. The players seemed so numbed with anxiety that they could barely find a red shirt with a pass. Even experienced campaigners like Gary Neville and Rio Ferdinand were struck by the crippling stress.
Sir Alex had appealed to United fans for a replica of the Chelsea atmosphere but the roar wasn't forthcoming as the fans appeared overcome by the strain of such an unexpected knife edge night.
Cristiano Ronaldo was the only United player who seemed relatively unaffected and he unleashed numerous efforts on goal but either keeper Quim or his wayward boots stumped him.
If anyone thought that lightning couldn't strike twice and the Estadioda Luz shocker 12 months ago was unrepeatable on home territory they were in for the fright of their lives after 27 minutes.
Simao's raid down the right saw the Benfica skipper square to the marauding right back Nelson.
Criminally there was not a soul intercepting, and the defender made hay with the freedom, unleashing a thunderbolt that even Edwin Van der Sar couldn't get anywhere near.
If anything, the astonishing jolt woke United up and the nerves dissipated to be replaced by a fierce determination and a more fervent support had the Reds surging forward. It was desperately frantic stuff at times rather than the fluency of United's Premiership football but at least they looked more and more dangerous.
Even the blow of not being awarded a rescuing penalty three minutes after the Benfica goal could divert the Reds from their quest.
Goalscorer Nelson was the culprit when a fumbled save by Quim from Saha's far post header was on its way back into the danger area and he stuck out an arm and deflected the ball back to his keeper.
The Portuguese outfit tried to disrupt United's growing momentum when they brought down Wayne Rooney and Paul Scholes as they powered through in separate incidents.
United clearly needed a breakthrough before half-time to avoid a return of frayed nerves and they got it through Nemanja Vidic.
The barnstorming Serb scored his first United Champions League goal when his marker Nuno Gomes fell in the box as Vidic went to meet Ryan Giggs' free-kick. Nothing was going to stop the powerful defender thumping home the equaliser.
It was difficult to see another scare blowing up in United's face again but you couldn't have imagined Copenhagen scoring in Denmark or Celtic snatching a winner in Glasgow.
You can never relax with the Reds.
However, there was a more comfortable feeling about the place when on-fire Ronaldo kept the party tricks on ice to fire a superb cross onto Giggs' head. The Welshman is not usually the recipient of such deliveries but he sure knew how to put it away, directing his header powerfully into the net after 61 minutes.
The relief was tangible when United finally decided the fans had been put through the wringer for far too long and Saha put the match beyond Benfica with another powerful header from a set-piece.