Only time will tell us whether the football Manchester United played in beating Newcastle so thrillingly two weeks ago signalled a new dawn under Jose Mourinho or merely a painful, brief flashback to better days at Old Trafford.
The safe money would be on the latter. The United flame has flickered and danced before under Mourinho before being extinguished by the restrictions of the manager's tactics. What is clear is that something must give at Old Trafford and it must give soon.
Mourinho's United cannot carry on this way. They cannot continue to puzzle and disappoint their supporters, taking them to the edge of despair before hauling them back again with the vague promise of something better.
Chelsea, Juventus, Everton. These teams stand before Mourinho and his players over the next eight days. If United are not seen to build on the dashing, brave and frankly quite out of character football they played in overturning Newcastle's two-goal advantage a fortnight ago, the chances are they never will. Mourinho remains adept at producing bespoke individual tactical successes.
He has done it against Liverpool in recent times and against Tottenham. Without doubt, he can do it at Stamford Bridge this lunchtime.
But they alone are not enough. United's football changed direction out of desperation against Newcastle and it will only mean something if that momentum carries on.
Asked on Friday if he had told his players to play a more expansive game, Mourinho was hesitant and his answers are probably better served if produced verbatum.
Question: The team played well in the second half against Newcastle, can you play that way for 90 minutes?
Answer: We try.
Q: What's the key?
A: The key is for the players to be able to do it.
Q: Are the players instructed to play the way they did in the second half?
A: This story of the attacking football. I still don't understand that story. Because for me you can only play attacking football when you have the ball.
Q: But there are different ways to play when you have the ball.
A: Yeah but you need the ball. When the opposition has the ball you have to defend.
Q: The second half against Newcastle. Is that what you want them to do?
A: Yes. It is. Yes. I want my team, when the opponent has the ball, I want the ball and you can only recover the ball if your opponent loses it or if you recover or if you provoke a mistake in your opponent for all that you need to defend. When you have the ball you can play a different way and that is normally adapted to the qualities of your players.
Q: When your team has the ball, can it be that way?
A: That is what I want.
Q: Do you need to be 2-0 down to play like that?
A: No.
The most generous take you can place on the above exchange is that Mourinho was being evasive.
If you wish to be less generous you could say he doesn't want to admit what we all suspect, namely that front-foot football is no longer his way.
The even less generous would maybe argue that Mourinho is merely as muddled as his team often tend to be.
On Saturday at Chelsea, it would be foolish to press Maurizio Sarri's team. Saturday is indeed perfect for some classic Mourinho cat and mouse. Beyond that, however, United have Juventus on their own pitch and then an Everton team at Goodison Park still making its way under a new coach.
So there are opportunities for something more akin to what happened against Newcastle.
As good as they were in striking back through Juan Mata, Anthony Martial and Alexis Sanchez, they were so poor in the first half that it is no wonder the United board are at something of a loss about what to do with the man they hired amid such optimism only two and a half years ago.
Chelsea under Sarri are fast and inventive but they are also physically diminished. We can expect to see Maroune Fellaini, Nemanja Matic and Paul Pogba deployed to exert some kind of physical advantage for United. It could work, particularly at set pieces.
On Friday Mourinho was asked if he would celebrate if his team scored or won and said he would be respectful to those who once fell at his feet.
It is a mystery as to why he would be. The Chelsea crowd have not been generous to their former manager for quite some time now.
More pertinent is this question. Will Chelsea supporters even recognise Mourinho and what he has now come to represent?