After a close-season soured by Mourinho's discontent over the lack of transfer activity, Sunday's 3-2 loss at Brighton & Hove Albion brought an early chorus of complaints from fans and former players about the state of the side.
United beat Leicester City at Old Trafford in the opening game of the season but Spurs present a very different quality of opponent.
The bare statistics suggest United are favourites, given that in the Premier League era Spurs have managed just eight wins against United, who have enjoyed 33 victories over the North Londoners.
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Even in the recent era, as United have lost their air of dominance, Spurs have lost on their last four trips to Old Trafford.
But Mauricio Pochettino's side have begun the new campaign well with wins over Newcastle United and Fulham and while they didn't make any moves in the transfer window they have kept together their impressive squad.
United's defence was at all sea on the south coast last week and it would be no surprise if Mourinho made changes in that department against a Spurs attack featuring Harry Kane, Dele Alli and Christian Eriksen.
England internationals Chris Smalling and Phil Jones are options should Mourinho decide against the partnership of Eric Bailly and Victor Lindelof who struggled at Brighton.
Champions Manchester City have picked up where they left off last season with two wins, including Sunday's 6-1 thrashing of Huddersfield Town, and they will expect to maintain their 100 percent record at promoted Wolverhampton Wanderers on Saturday.
New Arsenal manager Unai Emery has had a very tough start to life in the Premier League with Arsene Wenger's replacement having seen his side lose at home to City and at Chelsea.
The Gunners take on another team without a point to their name on Saturday when they host West Ham United.
The Hammers' pre-season optimism, following the appointment of Manuel Pellegrini as manager and heavy investment in new players, has been tempered by losses to Liverpool and Bournemouth.
Juergen Klopp's Liverpool have two wins and will look to show United how to deal with Brighton at Anfield on Saturday.
Chelsea have made a positive start under their new manager, Italian Maurizio Sarri, but face a tricky test at Newcastle United on Sunday.
(Reporting by Simon Evans, editing by Ed Osmond)
