The Terriers head to Old Trafford on the back of a five-game losing run that has left Wagner’s men four points adrift of safety in the Premier League.
Tackling the Red Devils at a venue where Town have a poor record was always going to be a big challenge for Yorkshire’s sole top-flight representative.
But Ole Gunnar Solskjaer’s appointment being followed by a 5-1 victory at Cardiff City that has brought the smiles back to a club where scowls had dominated during Mourinho’s final few weeks means that task has become even more daunting.
“I was surprised when the change of manager happened,” Wagner told The Yorkshire Post ahead of today’s trip across the Pennines.
“I really feel for him (Mourinho). This was nothing what a manager in general wants to see.
“I do not like it that managers get sacked, especially if we play them soon after like on Saturday (when Southampton manager Ralph Hasenhuttl was taking charge of only his third match).
“It is not the easiest, but, like always in life or in football, it gives you a chance and we will see what we can produce.”
The manner of Saturday’s defeat to Southampton, when the Terriers’ display was way short of the required standard in the top division, means few will give Huddersfield any hope of causing an upset today.
Not only do United boast the top-flight’s best Boxing Day record – 51 victories from 92 outings on a date that traditionally draws the biggest crowds of the season – but Town’s record at Old Trafford is also lamentable.
Huddersfield last tasted victory at the home of the Red Devils in 1930-31 and the 15 visits since then have brought 10 defeats and just five draws.
Little, therefore, to suggest an upset is imminent as Solskjaer makes his home bow as interim manager in front of a sell-out crowd that will include 3,129 visiting fans.
“Usually these are the games we want to have,” added Wagner. “They are what the Premier League is all about, exactly why we love the Premier League and why we wanted to be in the Premier League.
“Old Trafford on Boxing Day – I don’t think there are much better occasions. We will go there and try everything even if we know it is a difficult task.
“The good thing is we have some experience of Old Trafford. We played there last year, so this will not be our first time. We know we can’t make any mistakes. We also have to create.”
Wagner’s main injury concern surrounds Jonathan Hogg, who missed the 3-1 home defeat to Southampton after suffering a knee problem in training.
With Aaron Mooy and Danny Williams already out until the new year Hogg’s absence was keenly felt against a Saints side who were able to dominate midfield.
Terence Kongolo, who sustained a bang to his hip in the first half on Saturday, is expected to be fit for what on paper is comfortably the toughest game of the club’s festive schedule.
“We have to take the Southampton result on the chin and go to Old Trafford,” added Wagner, who is also without club captain Tommy Smith (hamstring) and midfielder Abdelhamid Sabiri (shoulder).
“Our problem on Saturday was we were not brave enough.
“In the first half the pressure that everyone spoke about affected us. We have to make sure this does not happen again as then you do not perform at your highest level.
“Do not be affected by it. Be independent from the circumstances. If we are not at our best level we will not collect points. We have to keep fighting.”
With trips to Fulham and Cardiff City sandwiching the January 2 home encounter with Burnley once today’s trip to Manchester is out of the way, Huddersfield can still bounce back from what has been without doubt a chastening December.
“We have every chance,” said Wagner when asked about his side’s survival prospects after collecting just 10 points and two victories so far this season. “There are 20 games to play and that is 20 chances to collect points.
“At the minute we are not very comfortable on numbers in midfield.
“Hopefully, Hoggy will be back, but we have lost four midfielders in two weeks. That can make things difficult.
“Everyone tried their best (against Southampton) and we believe in every one of our players.”
Last six games: Manchester United DDWLLW Huddersfield Town WLLLLL.
Referee: J Moss (West Yorkshire).
Last time: Manchester United 2 Huddersfield Town 0; February 3, 2018; Premier League.