Ole Gunnar Solskjaer crossed the Rubicon as Manchester United manager on Sunday, the day he was humiliated by predecessor Jose Mourinho in a 6-1 defeat against Tottenham at Old Trafford that might turn out to be the moment that triggered the search for his successor.

Mauricio Pochettino, who Mourinho replaced at Spurs last November, is still available and his shadow will loom ever larger over Solskjaer. And after such a brutal defeat, which featured an awful performance by United's players, it would be no surprise if the Argentine gets a call from executive vice-chairman Ed Woodward during the international break.

If that proves to be the case, Solskjaer can have no complaints. There really is no hiding place now, regardless of the hand he has been dealt by his bosses in the transfer market during the ongoing transfer window, which closes at midnight CET on Monday.

The fact is that, if Solskjaer does lose his job, he will have to accept as much blame as anybody else.

- Maguire 2/10 as United are humbled
- Son, Kane 8/10 as Spurs smash six

Unquestionably, he has been let down by the club during the transfer window; United are almost certain not to sign prime target Jadon Sancho before the deadline, while there has been no serious effort made to deliver on the manager's demand for a commanding centre-half, a necessity borne out by abysmal defending against Spurs.

Just as in Mourinho's final transfer window as United manager, during the summer of 2018, targets identified by the man in charge of the team have not been recruited and, as ever, the club are embarking on a deadline day scramble to get deals done, with free agent Edinson Cavani and Porto left-back Alex Telles expected to sign.

Solskjaer wanted Erling Haaland last December, but despite a personal friendship with the player's father and having worked with the young striker at Molde, Woodward was unable to get a deal done before Borussia Dortmund snapped up the FC Salzburg teenager. In addition to Sancho, RB Leipzig defender Dayot Upamecano is another target who has not come close to signing.

But every manager has to accept the frustration of failing to get the players he wants, and the key to the job is working with the resources available and making players better.

Solskjaer might argue that he has coaxed the best from Anthony Martial and brought through the undoubted potential of Mason Greenwood, but the majority of United's squad has regressed under his management.

Given what followed, it is worth remembering that United opened the scoring inside two minutes against Spurs, with Bruno Fernandes converting a penalty. But what followed was goal after goal featuring one shambolic error after another, evidence that Solskjaer's defenders perform as though they aren't properly coached.

When a team has had a man sent off -- United had Martial sent off for slapping Erik Lamela in the 29th minute when the score was 2-1 -- the professional mindset is to stem the damage and kill the game. None of that nous was on display and Solskjaer, hands folded on the touchline, did nothing to cajole or inspire his players into action.

Meanwhile, on the opposite side, this was a triumph that will quiet any critics who suggest Mourinho has lost his magic touch. Spurs were playing their fourth game in a week and made the worst possible start, but took the lead within seven minutes of going behind and thereafter cruised as their manager reveled in the circumstances.

Son Heung-Min and Harry Kane each scored twice for the away side, while French duo Tanguy Ndombele and Serge Aurier also netted to cap commanding displays. Mourinho has guided his club through a hectic period and Tottenham go into the international break with confidence growing and with Gareth Bale's return approaching.

By contrast, United's players were awful. If Paul Pogba, Luke Shaw and Harry Maguire do not pull on the red shirt again after their inept displays, they could have no complaints.

Pogba performed like a wrecking ball... against his own team. The foul on Ben Davies, which led to the penalty for Tottenham's sixth goal, was so bad that you would not see a repeat in a kids game. But Pogba is an £89 million midfielder with a reputation that far outweighs his contribution.

This is a United side that has conceded 11 goals in three league games so far this season and, for that, there can be no excuses. They were down to 10 men against Spurs, not seven, so there really can be no attempt to mitigate the embarrassing scoreline.

Just three games into the Premier League season, United are miles behind champions Liverpool and even trail pacesetters Everton by nine points, so can forget about winning the title for another year. Maybe nobody at Old Trafford believed they could win it anyway, but it is not even Halloween and they are already out of the running.

The big question now is how long United's owners, the Glazer family, will put up with such dismal performances and results. History shows they rarely act quickly; David Moyes, Louis van Gaal and Mourinho were all sacked months after the first signs of decline had set in, so Solskjaer might last for a good while.

When United and Spurs met in this fixture last December, the spectre of Pochettino overshadowed the game. Almost a year on, he remains unemployed but will not be available forever. As cameras panned to Woodward toward the end of his club's latest humiliation, he was seen texting on his phone.

If he was not making plans for a change in the manager's office, there will be a growing number who believe that he should have been.