Sheffield United will make the 50-mile trip to Old Trafford on Saturday evening, backed by an army of 8,543 supporters hoping to witness one of the greatest cup upsets - even for a team with their track record of achieving such feats.
Their is a name that is known around the world (seriously, Xavi referenced them in an interview last year), but having been exiled to League One for going on five years now, perhaps it's time to refamiliarise.
Here's five things you should know about 'Dem Blades', courtesy of
They're the original United
While Saturday's opponents may not be the most famous United, it was their Steel City counterparts who first adopted the now-popular suffix, in their early days as a cricket club.
Sheffield United CC were formed all the way back in 1854, long before the Uniteds of Leeds, Newcastle, Torquay, er, JEF and Muangthong.
Not only that, but the Blades' Bramall Lane home, where they have resided since their birth as a football club in 1889, is the world's oldest professional ground and hosted the first ever floodlit match.
DID YOU KNOW? Neighbours Sheffield Wednesday originally played at the Lane, and were known as the Blades until their move to Owlerton at the end of the 19th century, when they adopted their current nickname - the Owls.
Call them underdogs at your peril
The Blades have faced Premier League opposition nine times over the past three seasons and have lost just twice - both at the semi-final stage.
After seeing off Aston Villa and Fulham (via a replay) in this competition two years ago, United eventually came unstuck in their last-four tie against Hull City at Wembley, where they fell to a heroic 5-3 defeat.
And they came even closer to making last season's Capital One Cup final, with only a late equaliser on the night from Tottenham's Christian Eriksen dumping them out at Bramall Lane.
Despite this, there is a sure-fire way to beat them in the cups: dress as either Burton Albion, Mansfield or Hartlepool.
This is their fifth FA Cup meeting with the Red Devils
...and the previous four occurred during a five-year spell at the start of the 1990s! Perhaps surprisingly, n
Saturday's clash marks the 20th and 21st anniversaries of the two most recent cup meetings - on 9 January 1994 and 9 January 1995 (when Eric Cantona pulled off the above).
Who's their manager?
Sheffield United won't be the only third-tier side Nigel Adkins has managed against the Red Devils in the FA Cup.
Five years ago the University of Salford physiotherapy graduate saw his Southampton side narrowly beaten 2-1 by Sir Alex Ferguson's men at St. Mary's, with Michael Owen and Javier Hernandez on target for United and current
The 50-year-old has met Saturday's opponents once since, losing 3-2 courtesy of a Robin van Persie hattrick three-and-a-half-years ago. Schneiderlin, incidentally, had given Southampton a two-goal advantage.
Which one's the danger man?
That would be Billy Sharp. The boyhood Blade is back for a third spell at Bramall Lane - the fourth club at which he's worked under Adkins.
The 29-year-old is a born poacher - scoring 11 goals since his return last summer - but his all-round game seems to have improved since his last spell in Sheffield 2, with four assists also arriving this term.
Fit-again right-back John Brayford is an unexpected threat at both ends, while the pace of former non-league striker Che Adams is also something for the Red Devils to be wary of.