Kenny Dalglish failed to get the dream start he was looking for as United ensured his second stint as the new Liverpool boss began with a defeat.
Dalglish arrived from Dubai on Saturday night after accepting the challenge of reviving the Merseysiders' fortunes, which have plummeted dramatically in recent times, culminating in Roy Hodgson's dismissal.
And he certainly brought more conviction to his players and Liverpool's supporters.
It will take rather more to create a winning team though, and while Dalglish can take heart from the way his side battled back following Giggs' controversial second-minute penalty and the dismissal of captain Steven Gerrard for a nasty first-half challenge on Michael Carrick, the Scot knows there is so much work to do.
Still, his name brings hope, even if time has moved on since February 22, 1991, when Dalglish resigned in the wake of an epic 4-4 draw with Everton.
Indeed, just eight days after Dalglish's dramatic decision to quit the club he will forever be linked with, came another significant day in English football - Giggs' United debut.
That Giggs boasts a record 11 Premier League winners' medals, 855 appearances and 157 goals for the Old Trafford outfit just emphasises the time that has elapsed since Dalglish bestrode an Anfield outfit that were still worthy of their status as a football giant.
There was a symmetry therefore about Giggs confidently striding up to dispatch a second-minute penalty that punctured so much of the optimism within the Dalglish bubble.
Not that the Scot would have been entirely convinced by Howard Webb's penalty award. Few who saw the replay were, although Daniel Agger's unwise decision to stick out a leg did offer Dimitar Berbatov something to fall over.
Unfortunately for Dalglish, it was not the last time he had reason to curse Webb, who steered the game towards its eventual outcome with two crucial decisions around the half hour.
The first was a non-decision when Rafael thudded into Raul Meireles with a tackle that won the ball, but was also two-footed.
Had Webb taken action for that, Gerrard might have thought twice about his own ill-fated lunge.
But the World Cup final referee kept his cards in his pocket and waved play on.
The same did not apply when Gerrard launched himself into England team-mate Carrick, going over the top of the United man, which Webb deemed reckless enough to merit instant dismissal.
Having taken all this into account, and the remainder of an otherwise positive opening 45 minutes for his team, Dalglish loitered for just long enough after the half-time whistle to suggest he might take issue with Webb. In the end, he opted not to bother.
The Scot's interval team talk could at least have reflected on decent opportunities for Fernando Torres, denied the chance to exert his superiority over Nemanja Vidic by the United skipper's absence, Gerrard and Maxi Rodriguez.
He must also have known that United would dominate possession in the way his own side had done before Gerrard's departure.
And if Javier Hernandez had been able to glance Darren Fletcher's right-wing cross into the bottom corner a couple of minutes after the restart, Liverpool would have had nothing worth fighting for anyway.
As it turned out, the Mexican was off target. And though Liverpool did spend long periods chasing possession, roused by their supporters, who were gaining their own voice through Dalglish, they refused to give up.
Ryan Babel brought a low save out of Tomasz Kuszczak before Fabio Aurelio sent a free-kick curling towards the top corner, forcing the Pole to claw the ball away.
It took United some time to re-establish dominance, although when they did, two blocked shots, for Berbatov and Rafael, rejected penalty appeals for Jonny Evans and Giggs, both far more plausible than the one Webb gave, plus an excellent save from Reina to deny Patrice Evra, were scant reward for a thrilling melee.
The sight of Michael Owen being introduced for United 16 minutes from time just added another surreal dimension to an amazing day.
There was no goal for Owen against his old club, as Anderson and Evra went closest to increasing United's advantage before the final whistle.