Manchester United suffered their joint heaviest Premier League defeat with a 6-1 home thrashing at the hands of Tottenham to further darken the bleak mood at Old Trafford.
The Norwegian might find his position coming under scrutiny after such an embarrassing defeat, while he will have to hope his side do significant transfer business in the next 24 hours.
United, who are reportedly close to bringing in Porto full-back Alex Telles and Uruguayan striker Edinson Cavani but will need significantly more, had gone in front through another Bruno Fernandes penalty in the opening two minutes.
However it quickly descended into their worst defeat since Manchester City triumphed 6-1 here nine years ago.
They had to play 60 minutes with 10 men as Anthony Martial was sent off, but they were cut apart by a rampant Tottenham, with Son Heung-min and Harry Kane scoring twice and Tanguy Ndombele and Serge Aurier also bagging.
Victory will be sweet for Spurs, who have scored 11 goals in their last two away games and still have Gareth Bale to come into their side after the international break.
This win comes on the back of four games in eight days, but they showed that under Mourinho this season they could challenge at the top end of the league.
No one could have seen what was to come after the opening 30 seconds.
Mourinho has made several sly digs in the media recently about the amount of penalties United get, but even he would not have expected referee Anthony Taylor to point to the spot after only 31 seconds.
The Portuguese cannot have too many complaints with this one, though, as Davinson Sanchez clearly tripped Martial and Fernandes as ever made no mistake from 12 yards.
But that was as good as it got for United as their afternoon descended into one of their worst in recent memory.
Things started heading south just two minutes after going in front as they gifted Spurs a leveller.
Harry Maguire was the main culprit, mis-timing his header back to David De Gea, with Luke Shaw then allowing Erik Lamela to harass him and the loose ball fell to Ndombele to fire in from close range.
Three minutes later Spurs exploited massive holes in the United defence as Kane took a quick free-kick to play Son in and the South Korean made no mistake, coolly clipping home.
United were been cut wide open time after time as Son, Aurier and Lamela all went close before it continued to get even worse for United as Martial was sent off just before the half-hour.
He grappled at a corner with Lamela, who appeared to put his forearm towards Martial’s neck and the Frenchman retaliated by slapping the Spurs attacker and received a straight red card.
Three minutes later and United again committed defensive suicide as Eric Bailly’s misplaced pass was intercepted on the edge of the area by Kane, who was soon on the end of Son’s pass to fire home.
Mourinho’s men then became the first ever Premier League team to score four first-half goals against United as they made use of acres of space down the right, with Aurier playing in Son to roll in from close range to score his second of the game.
Solskjaer made two changes at the break, bringing on Scott McTominay and Fred, but they could not stem the tide as Aurier made it five in the 51st minute.
This was a real slick move as Ndombele, Lucas Moura and Pierre Emile-Hojbjerg all combined to play in the right-back who rifled into the bottom corner.
Spurs kept going and scored a sixth with 11 minutes remaining as they got a penalty of their own.
Ben Davies was wiped out by Paul Pogba and there was little doubt about the end result as Kane fired home his ninth goal of the season.