Sir Alex Ferguson's most famous quote, fittingly, revolved around his long-standing obsession with Liverpool. Twelve years on, that bold and expletive-laced declaration in September 2002 about knocking the Anfield club 'off their perch' remains oft-quoted by both clubs' fans.
Rejuvenating a side that had finished 10 points adrift of champions Arsenal in the previous campaign, he claimed, was a minor challenge compared to surpassing a domestic and continental silverware haul that had lain largely dormant on Merseyside for almost a decade.
Liverpool were always the benchmark for Ferguson's United, and vice versa - even when they endured relatively barren campaigns and occasional yet futile title challenges. But with the dust barely settled on the legendary Scot's retirement, the trend is already reversing.
United are a mere shadow of the team Liverpool once aspired to surpass. Where they used to look down on their Premier League peers, they now find themselves craning their necks skyward. They have not been knocked off their perch; they have sleepwalked off it.
There is little resemblance with the team that strode to the title 12 months ago - and contrary to Juan Mata's ambitious attempt at channeling the spirit of Eric Cantona, the storm clouds lingering over Old Trafford are unlikely to pass for some considerable time.
Even removing the increasingly beleaguered David Moyes will not save United from a downfall evocative of the one Liverpool suffered during the Premier League's formative years.
The parallels that exist between the previous power shift across the East Lancs Road and the one currently at play are remarkable and warn of troubling times ahead for the Red Devils.
Like Liverpool, they have enjoyed unbridled dominance of England's top flight for decades thanks to their seemingly unshakable dynasty. Yet Ferguson's departure, staggeringly, appears to have decimated the foundations upon which United's winning habit were forged.
When Michael Thomas' injury time strike in 1989 snatched the title from Liverpool's grasp, it should have served as a warning sign that their domestic domination was finally in danger of being challenged but such thoughts were, understandably, far from a priority for a club still coming to terms with the horrors that had unfolded in the Hillsborough a month prior.
That was reflected in their transfer plans that summer, with Kenny Dalglish identifying only one genuine first-team addition of the two signings made, in the form of defender Glenn Hysen. The other, Steve Harkness, would not make his first-team debut for a further three years.
Liverpool went on to reclaim the title 12 months later, finishing nine points ahead of second-placed Aston Villa but as the Kop boss continued to shoulder the emotional burden from events in Sheffield, up until his resignation in 1991, further players ill-suited to their signature style and ill-equipped to cope with the psychological pressures of donning the famous red shirt followed.
Similarly, United failed to heed the warning of a need for fresh longevity when Sergio Aguero's 93rd-minute winner on the final day of the 2011-12 season saw Manchester City snatch the title from their local rivals by the solitary virtue of a superior goal difference.
That summer, Ferguson bolstered his options but it would be predominantly cosmetic. Robin van Persie's goals ensured the title would return to Old Trafford with an 11-point margin over runners-up City, but the likes of Shinji Kagawa, Nick Powell and Alexander Buttner were never going to be long-term solutions.
As with Graeme Souness at Liverpool, his successor has made inadequate additions. Marouane Fellaini finds himself cast in the Mark Walters role, a trusted ally signed from his manager's former stomping ground, while Mata assumes Paul Stewart's mantle of ineffectiveness. And like Harkness, it is unlikely Guillermo Varela will find himself, at 20, staking a claim in the United first-team ranks for several years at least, if at all.
Souness' willingness to make rapid and wholesale changes may have prepared Liverpool for the realities of the Premier League but in doing so unseated the winning mentality the club had bred for over three decades. Moyes' dissolution of Ferguson's backroom, replaced with his Everton coaching staff, has had a similar effect for United.
A lack of leadership at executive level was equally fallible. The successive hierarchies at Anfield have been unable to fill the void left by the partnership of Sir John Smith and Peter Robinson, just as United have appeared amateurishly inept since Ed Woodward replaced the outgoing David Gill last summer.
Last Sunday, when confronted with the reality of their toothless and humiliating defeat, Old Trafford issued a final roar of defiance. Where Liverpool used to chant '5 times', in reference to their European Cup haul, United eulogised about their record-breaking 20 titles.
It was nothing more than posturing in the face of their most hated rivals. Like Liverpool in previous years, memories may be all that United have to cling to for the foreseeable future.