Instead of being an occasion to savour as he might have imagined, the two-legged encounter with Gus Poyet's side has taken on 'must-win' proportions given it is United's only realistic chance of domestic silverware this term as it follows their recent exit from the FA Cup..
Way off the pace in the Premier League and eliminated from the major cup competition at the third round stage for only the second time in three decades, should the Red Devils fail to advance to a Wembley final at the expense of the side rock bottom of the table, terrace disenchantment with Moyes will start to solidify.
In turn, that would only further erode the confidence of a squad that won the title by 11 points during Sir Alex Ferguson's final year in charge, an incredible effort given what has followed.
Yet Moyes shows no signs of flinching, despite the increased pressure and scrutiny, from outside the club at least.
It was always his plan to make changes on Wearside. And that is not going to alter.
"Our approach to Sunderland had to have the FA Cup game in mind because it was two matches in 48 hours," said the Scot.
"It has always been vital for us to win every game and get to every final if we can.
"There is a job in front of us in every competition we enter. We have got to overcome Sunderland in a two-game match to reach the final.
"It will be a difficult game and difficult to judge exactly how the first leg will go.
"But we will try to get ourselves to the Cup Final if we can."
It is to Moyes' advantage the changes he planned will strengthen his team.
Michael Carrick, Patrice Evra and Nemanja Vidic should all return after missing the Swansea game, at a stroke providing some much needed experience.
And whilst Wayne Rooney is troubled by a groin problem, the mere fact he was able to play against Tottenham on New Year's Day suggests he will push himself through a game of even more importance.
The unknown is Robin van Persie, who did appear to be nearing a return after a thigh problem, but about whose comeback Moyes spoke in negative terms at the weekend, when the Scot claimed not to know when his key striker may reappear.
Even without the back-to-back Golden Boot winner, United are still expected to overcome a side they have already beaten this term, thanks to the first two goals of Adnan Januzaj's fledgling Old Trafford career.
However, with Manchester City as likely final opponents, the silverware that could buy Moyes some valuable time as he attempts to assert his own authority on the Red Devils cannot be taken for granted.
The Scot's frank admission of January not being the best time to bring in new players hardly helps generate a feeling of optimism amongst fans.
And an obvious lack of impact made by Marouane Fellaini since his £28.5million move from Everton may make Moyes even more tentative about spending big sums this month.
Yet without reinforcements, in midfield particularly, it is hard to see the situation improving to any great degree, which will put United's hopes of a top four place in peril.
Former United striker Lou Macari summed up the present malaise on MUTV: "It used to be teams came to Old Trafford and didn't get a kick. It was one-way traffic for most of the game and they went away losing.
"The last three or four games at Old Trafford has not been the case. We have been struggling to get near them."