Both sides have endured tough times of late in their respective league campaigns, so they are likely to welcome the distraction provided by the world's oldest cup competition when they meet at the iPro Stadium.
A 2-0 win over Fulham on Boxing Day sent the Rams to the top of the Championship standings.
For all intents and purposes, at that stage Paul Clement's men looked a safe bet to gain promotion back to the Premier League for the first time since the 2007-08 campaign.
However, just two points have been collected from five outings since then, which in turn has seen them drop down to fifth position - seven points adrift of leaders Hull City.
While that run will certainly be a cause of great concern for Clement, he is bound to be particularly worried by the number of goals that his side have shipped in recent weeks.
A 3-0 home defeat at the hands of Birmingham City was followed up on Monday evening by a 4-1 loss away at Burnley.
They are at least able to boast a decent home record this term. The hammering inflicted by Birmingham was just the second time in the Championship that Derby have suffered defeat in front of their own supporters.
Recent form (all competitions): DLWDLL
For weeks now journalists have had a story on file awaiting publication regarding Louis van Gaal's departure from Man United, but the Dutchman has so far defied the intense speculation and frustrated the eager hacks as he claws on to his job at Old Trafford.
To the 64-year-old's credit, he was in bullish mood during his press conference ahead of the trip to the East Midlands. He hit out at the reporters that had suggested his time with United was coming to an end, branding the stories "awful and horrible".
Van Gaal will now be hoping that his players show a similar fighting spirit against Derby, while the travelling support yearn to see more attacking intent from their team.
After all, those that have attended United's last two fixtures - against Liverpool and the Saints - have seen the Red Devils record just one shot on target in each encounter. One of those - from Wayne Rooney - flew into the roof of the net at Anfield, while the other was a speculative strike from distance by centre-back Daley Blind that caused no trouble.
Recent form (all competitions): DWWDWL
United's Italian full-back Matteo Darmian limped off following a collision during the game against Southampton and he will not recover in time to feature in this encounter.
Experienced midfielders Michael Carrick and Bastian Schweinsteiger are in line to return to the squad from injury and suspension respectively, but Ashley Young, Marcos Rojo and Phil Jones are all out.
As for Derby, boss Clement has no new injury problems to contend with.
Derby possible starting lineup:
Carson; Christie, Keogh, Shackell, Warnock; Thorne, Butterfield, Johnson; Ince, Blackman, Martin
Man United possible starting lineup:
De Gea; Borthwick-Jackson, Smalling, Blind, Varela; Schneiderlin, Carrick; Herrera, Lingard, Martial; Rooney
Head To Head
When it comes to the FA Cup, it would be fair to suggest that Derby do not enjoy facing United.
They have lost all six of the ties between the two teams, including the most recent one in 2009 when United ran out 4-1 winners.
In all competitions, Derby have won only three of the last 19 games involving the pair in all competitions.
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We say: Derby 0-1 Man United
Those tuning in to see an entertaining FA Cup tie could well be left feeling short changed. Neither of these sides are pulling up any trees, so if it is going to be decided, one goal is likely to be enough. The experience is with the visitors, who should just about nick it, but don't be surprised if it ends 0-0.