United already trail title favourites Manchester City, Liverpool and Chelsea by three points after a dreadful display in losing 3-2 to Brighton last weekend and that gap could have doubled by kick-off at Old Trafford (1900GMT) with all three expected to win again this weekend.
City travel to Wolves and Liverpool host Brighton on Saturday, while Chelsea travel to Newcastle on Sunday.
Spurs are also yet to drop points after defying off the field distractions to see off Newcastle and Fulham.
Mauricio Pochettino’s response to not signing a single player in the transfer window and delays over the club’s move to a new stadium have been a lesson in diplomacy for Mourinho.
Rather than voice his frustration, Pochettino has consistently called for unity between the board, squad and fans and has been rewarded in the early weeks of the campaign.
United, by contrast, look anything but living up to their name with divisions emerging between executive vice-chairman Ed Woodward, key players like Paul Pogba and Mourinho.
Woodward’s failure to answer Mourinho’s pleas for a new central defender was punished as Eric Bailly and Victor Lindelof were exposed in defeat at Brighton.
But both players were brought in at a combined cost of £60 million ($76 million) since Mourinho was appointed and the Portuguese coach has equally failed to harness their potential or get the best out of an expensively assembled squad.
Woodward may now be regretting hiring Mourinho rather than going after Pochettino, who has led Spurs into the top four for each of the past three seasons on a fraction of the resources.
The Londoners have lost 1-0 on each of their last three league visits to Old Trafford, though, and are also seeking revenge for defeat in last season’s FA Cup semi-finals.
Reversing that run would be a strong statement of intent that they and not United will rival City, Liverpool and Chelsea for the title.
© Agence France-Presse (additional edits from Cillian Cunningham)