Should the beleaguered Magpies win, it's said the Special One's only hope of remaining in charge is "the lack of a viable alternative," with rumoured favourite Zinedine Zidane thought to "be distancing himself from the job."
As for the Red Devils, they have endured a poor run of form that has seen them draw at home to Wolverhampton Wanderers and Valencia, exit the Carabao Cup at Championship side Derby County's hands—also at Old Trafford—and a 3-1 defeat at West Ham United.
It is not just the results but also the performances that have disappointed United legend Paul Scholes, who has been bored watching his former team play:
Mourinho told BT Sport after the 0-0 draw with Valencia that his players "don't have the technical quality to build from the back." Sky Sports' Adam Bate feels that's an unhelpful line to take:
Even limited players can play attractive football if utilised correctly, and what's more, Mourinho has spent close to £400 million on his squad, so it's largely his responsibility if the players he has aren't capable of meeting his demands.
Football writer Liam Canning has been a vocal supporter of the manager during his time at Old Trafford, but he is one of many who would like to see the back of him:
Should United fail to beat a struggling Newcastle side at home, it would be difficult see a light at the end of the tunnel for Mourinho.
There is an international break after the match, giving the club plenty of time to act and bring in a new manager.