The 20-time English champions have dropped eight points in their last four Premier League fixtures, with a 1-0 loss at Chelsea last time out sending them into the international break on a low.
It will now be up to Mourinho to coax a performance out of his side, with the eight-point gap between them and leaders Manchester City being a cause of real concern for United fans. Another failure to pick up the full three points against Newcastle would leave the Red Devils facing up to the very distinct possibility of another season on the outside looking in on the league title race.
MAN UTD INJURIES
There should finally be a deeper squad for Mourinho to choose from this weekend, with the two-week gap between games helping some of those players undergoing recovery to return to peak fitness.
Michael Carrick should be available having stepped up his training regime in recent weeks following a calf issue, while Marouane Fellaini is likely to be among those considered for a start having returned to the side as a substitute against Chelsea a fortnight ago after three weeks on the sidelines with a knee injury.
United had hoped that Paul Pogba might be back in contention for the visit of the Magpies following two months out with a hamstring pull, but a late decision is likely to be made regarding the Frenchman's fitness. Marcos Rojo returned to action for the first time in seven months after ACL damage for the Under-23s on Wednesday but will be asked to step up his recovery further before being exposed to first-team action, while Zlatan Ibrahimovic is training again and at a push could be ready to come off the bench following a similar injury.
Phil Jones should be free to make a 16th consecutive Premier League start despite having limped off early during England's 0-0 draw with Germany with a calf problem. The ongoing streak constitutes the defender's longest unbroken run of league starts in his United career.
MAN UTD SUSPENSIONS
There are no suspension issues for the home side, with none of their players being banned or even on the verge of a one-match prohibition. While Newcastle have nobody missing through disciplinary issues, a yellow card on Saturday for Isaac Hayden would rule him out of the home fixture against Watford on November 25.
MAN UTD POTENTIAL STARTING LINE-UP
Jose Mourinho is expected to return to a four-man defensive shape for the visit of Rafa Benitez's men, with Eric Bailly and Phil Jones set to start together in the heart of the defence for the ninth time in 12 league fixtures this term.
There could be a personnel change in the centre of midfield should Marouane Fellaini prove he is 100 per cent fit, with Ander Herrera the most likely player to step down. Henrikh Mkhitaryan's place may also be under threat following a recent run of poor form, with Juan Mata and Jesse Lingard standing by for a call-up, while Marcus Rashford should again get the nod to start ahead of Anthony Martial on the left.
Romelu Lukaku will continue as the spearhead of the attack, despite having failed to score in his last seven club fixtures, although he is fresh off the back of having become Belgium's all-time record goalscorer over the past week with two goals in the draw with Mexico and the only strike in the narrow victory over Japan.
NEWCASTLE UNITED TEAM NEWS
Newcastle's main concern this term has been scoring goals, with captain and centre-back Jamaal Lascelles currently sitting level with centre-forward Joselu as the Magpies' leading goalscorer on just two. Such timidity in front of goal has seen the Geordies record just one win and a total of four goals in their last six matches, diluting the promise shown earlier in the season when they beat West Ham, Swansea and Stoke in consecutive matches.
It is generally accepted that Rafa Benitez has got the side punching above their weight though, and a pending takeover could really help to kick the club on should it materialise. In the meantime, the Spaniard will look to continue getting commanding performances out of the likes of Matt Ritchie, Isaac Hayden and Jonjo Shelvey in midfield.
One immense positive in their games this season has been their stubbornness at the back, and they have only twice conceded two goals in a game. The caveat behind that stat though is that Newcastle have yet to face any of Manchester United, Manchester City, Chelsea and Arsenal, and with skipper Lascelles a late fitness concern ahead of Saturday's game due to an ankle injury they could well be forced into a change in the backline after going with the same quartet in their last four matches.
BEST OPTA MATCH FACTS
Manchester United have won 22 and lost just one of their last 32 league games against Newcastle United at Old Trafford (W22 D9 L1) – 0-1 in December 2013 courtesy of a Yohan Cabaye goal.
Indeed, the Magpies have lost 84 matches in all competitions against the Red Devils, more than versus any other side in their history.
At Old Trafford, Man Utd are unbeaten in 22 Premier League games (W12 D10 L0), winning the last six in a row without conceding. They last won seven consecutive home league games without shipping a single goal back in March 2010.
Rafa Benitez has lost five times against Jose Mourinho in the Premier League - only versus Alex Ferguson (8) has he suffered more defeats in the competition (also 5 vs Arsene Wenger and Harry Redknapp).
Benitez has won four of his 13 previous Premier League matches against Man Utd as manager (P13 W4 D1 L8) - only Arsene Wenger (12), José Mourinho (5) and Gérard Houllier (5) have won more against the Red Devils in the PL.
Benitez could become the first manager in Premier League history to win at Old Trafford with three different away clubs, having won there with Chelsea and Liverpool previously – only Martin O’Neill (with Leicester and Aston Villa) has also won there with two different clubs.
TV COVERAGE & KICK-OFF TIME
The match at Old Trafford kicks off at 17:30GMT on Saturday, with TV coverage in the UK on BT Sport 1 beginning at 17:00.