The air of positivity that has followed Erik ten Hag since he took over at Manchester United last summer is showing signs of fading after the 3-1 home loss to Brighton.
The high-flying Seagulls have now completed four straight wins over their more illustrious opponents and this was surely the most worrying of the quartet, coming as it did with apparent ease.
Make no mistake, Brighton were 3-1 winners and fully meritorious of that scoreline. They looked to be playing within themselves and the home side were not able to muster any sort of telling blow in response.
For ten Hag, the most worrying moment might have been his decision to withdraw Rasmus Hojlund before the mid-point of the second half, a change that was met with a chorus of loud boos around Old Trafford.
The Dutch coach is facing a problem that has become all-too familiar for United since Sir Alex Ferguson's dynasty came to an end.
Ferguson's United dominated English football for a generation, making them the pre-eminent force of the Premier League era. Even at the end, the Scot managed to sign off with a title win with a side that was starting to creak.
A succession of high-profile managers have come and gone since, with often similar outcomes. Cup successes have been become the height of the Red Devils' aspirations, while neighbours Man City have settled into their role as kingpins of the English game instead.
Manchester United are still capable of big wins, big performances and 'statement' results. They are, though, reminiscent of the late mid-to-late 1990s Liverpool in that nobody really takes them too seriously as a genuine title contender nowadays.
Like their fiercest rivals then, United are struggling to come out the other side after a period of sheer domination ended.
It would take Liverpool until 2020 to finally end their long wait for a title. Taking an holistic look at where Man Utd stand now, it's not that hard to imagine they'll be left waiting quite some time before they get back to England's domestic summit.
They are already 66/1 also-rans in the title race this season, while a quote of 11/4 suggests that returning another top-four finish is going to be problematic.
Like David Moyes, Louis van Gaal, Jose Mourinho and Ole Gunnar Solskjaer before him, Ten Hag is probably starting to realise the sheer scale of the challenge that exists in trying to awaken a sleeping giant.
Brighton's latest win at Old Trafford was a dominant effort. Roberto de Zerbi's side had more possession, more shots on target, more clear-cut chances and an expected-goals return that doubled that of their hosts.
Danny Welbeck's opener for Brighton saw Victor Lindelof and Lisandro Martinez cut wide open at the heart of the United defence.
The Red Devils have conceded 10 goals in their last four games and have also conceded more than one goal in four successive league matches for the first time in 44 years.
Getting at this Man Utd team isn't that hard to do. Casemiro is supposedly the protection officer in midfield, but the 31-year-old Brazilian was leg-weary against Albion and was hauled off not long after the hour.
Captain Bruno Fernandes was ineffectual for much of the game and there remains a real doubt over the Portuguese as a leader, especially when the chips are down.
Marcus Rashford was bright at times in attack, but the England man was also symptomatic of United's problems.
At one stage in the second half, the Seagulls played the ball out from the back and around Rashford, with the forward jig-jogging around as the opposition made ground. It was all too easy.
Christian Eriksen was another who offered a below-par performance and it appears unlikely that a midfield containing the Dane and Fernandes will ever become industrious enough to cope with a confident passing unit like Brighton.
Ten Hag can point to players missing from his matchday squad right now.
Summer signings Mason Mount and Sofyan Amrabat watched from the stands, while Antony and Jadon Sancho were not available alongside the likes of Rafael Varane and Luke Shaw.
But would Manchester United be a different proposition even with those additions? It's tough to see it happening on recent trends.
Mount's form had already started to dip before his £55million switch from Chelsea and it's asking a lot of the 24-year-old to become a catalyst for United.
The much-maligned Harry Maguire was on the bench yesterday. His summer move to West Ham didn't materialise and he doesn't appear high up on the pecking order for ten Hag.
Next stop for Ten Hag and his side will be Munich on Wednesday and a Champions League date with Bundesliga champions Bayern.
The home side are 8/15 to win that one, with United at 9/2, and the likely outcome is a routine success for the Germans.
Harry Kane, the player United coveted for so long, will be licking his lips at the chance to shine in his first Champions League appearance for his new club.
Kane scored a relatively modest five goals in his 19 games against United as a Spurs player, but will fancy his chances of adding to that tally.
Alongside them in Group A are FC Copenhagen and Galatasaray. United are 1/5 to qualify from the group, but anyone who witnessed Brighton's stroll around Old Trafford will be wary of that price.
With Burnley, Crystal Palace and Sheffield United to come in three of the next four league games, ten Hag will hope to steady the ship before a Manchester derby in late October when champions City come calling.
Also between now and then is a Carabao Cup home tussle with Crystal Palace on 26th September.
As has been the case for the best part of a decade, United's best hopes of silverware are likely to be in the two domestic knockout competitions.
They are a match for any side on their day, but that day is much less frequent now and for Ten Hag, changing that culture remains the ultimate test.
Ferguson famously wanted to knock Liverpool from their perch when he took over at United.
He did, and then some, but now the Red Devils find themselves having inherited a much-less coveted position that once belonged to the Anfield side - the Spice Boys could turn it on every now and again, but couldn't be relied on.