Well, it was good while it lasted.
A gritty, backs to the wall smash and grab win against our biggest rivals was meant to be the start of something: a launchpad to lift United out of the gloom and into a momentum building run of wins and a surge up the table.
It's almost as if Anfield never happened: the euphoric outpouring of joy has been replaced by a deadening reality that it was- as we've seen so many times before under Louis van Gaal- another false dawn.
It's almost as if the phrase "two steps forward and one step back" was created for LVG's United tenure.
He did a fair job last season- stabilising the side that finished seventh under David Moyes to take us back into the Champions League through the qualifiers and into this season's group stage.
But even then you still felt we should have done better.
After the 4-2 victory over City on 12 April- the sixth win in succession- United sat second and four points ahead of the neighbours but after that we suffered three straight defeats and won only one of our last six games to finish the season tamely.
Having fulfilled his remit and got us back into not only Europe but the Champions League, the next logical progression seemed to be a realistic tilt for the title as Van Gaal set out his vision and three-year plan for the remainder of his contract.
As recently as early December, United were looking good for that challenge with a ten match unbeaten run but since then we've crashed out of the competition we worked so hard to qualify for and slumped to an eight-game winless run (it's now two wins in ten league games).
We thought we had turned the corner against Swansea only to edge unconvincingly past Sheff Utd and draw with Newcastle in a thriller before the win against Liverpool.
Our inability to build a run of results was put down partly to the crippling injury list which has far from aided Van Gaal but also a lack of confidence brought about by the slump in form.
That is what made today's result so disappointing.
We should have come into Southampton buzzing with the Anfield high under our belts, but instead slipped back into the soporific slumber that is rapidly becoming this side's trademark.
Adnan Januzaj's return to the team was supposed to provide us with a further lift but instead it was he who conceded the free-kick that led to Austin's winner.
We've made no progress under Van Gaal- his multi-million £ squad are lurching from one setback to another- and, with the fans now almost entirely against the Dutchman, only Ed Woodward knows how long he can continue to go on.