MOMENTUM can be a dangerous thing if it leads to complacency. Jose Mourinho, no doubt, understands this better than most. Even as Manchester United have come together over the past month or so, racking up nine consecutive victories in all competitions – Mourinho’s longest streak since 2011, when his Real Madrid side won 15 in a row – he has preached caution, musing about what a formidable task it will be to rebuild a team ravaged by the mistakes of the van Gaal-Moyes era.

This pumping of the brakes is somewhat self-serving of course. United’s resurgence is not built on sand and, even before the run of victories, they were out-performing their results. Though his claim of having “conquered England in three months” might be a tad bombastic, Zlatan Ibrahimovic is scoring goals at a rate confounding the sceptics who thought he couldn’t cut it in the mighty Premier League. Paul Pogba is making the team his own, the defence is solid, if not Mourinho-like, and there’s definitely a bounce in the United step. Yet the positivity could be quickly undone and that’s what he’s guarding against.

More broadly, the challenge for United is not to go the way of today’s opponents, Liverpool: dominant for two decades and now more than a quarter of a century removed from a league title. Sure, three years – barring a miracle, four, with this one – isn’t comparable to Liverpool’s drought. But the threat is there. What United don’t want is a generation of fans growing up without memories of being English champions.

And it is juxtaposed against a competition that won’t go away. From Chelsea to Manchester City to Arsenal, the other pretenders have comparably deep pockets and, crucially, one of the side effects of the Premier League and the globalised football economy is that their status is unlikely to change.

The risk is a “new normal” that’s an awful lot like Liverpool’s: a club playing catch-up vis-a-vis its glorious past. In Liverpool’s case, there’s another wrinkle: wealthy owners who are ultimately businessmen. They won’t simply spend their way back to the top but, instead, need to get creative, approaching break-even in transfer markets and hiring a man like Juergen Klopp, a visionary who is more of a giant-slayer than a giant.

Today’s clash – and Manchester City’s trip to Everton – has been hyped to high heaven by the folks at Sky, this time with a ridiculous Merseyside v Manchester tag. It’s nothing of the sort. But the consequences may be far-reaching. A convincing victory for United would cement their status as comeback kids and give Mourinho more of the power – especially in terms of transfers – that he so craves.

He has said he doesn’t expect to do business in January and that may be true – though the club are still talking to targets like Benfica’s Victor Lindelof and Monaco’s Tiemoue Bakayoko – but it would set him up nicely for the summer. And with a “soft” set of fixtures right up until the Manchester derby in a month’s time – Stoke, Hull, Leicester, Watford – by the time he crosses swords with the old enemy Pep Guardiola, he might even be in a position to pass him in the table.

For Klopp, there’s the obvious need to turn the Premier League into a genuine title race. But it’s also about showing that his style of football isn’t so physically taxing that his side collapse down the stretch, as has happened in the past. And proving that they can compete without Sadio Mane (off at the African Cup of Nations) and with Philippe Coutinho only just returning from injury. It’s a tall order and you only wonder what Klopp could do with more resources. But a victory at Old Trafford wouldn’t just make a statement, it might even get him some of the transfer help he needs to truly challenge for the Premier League.

The flip-side is that we get what we had the last time these two sides met. A Mourinho bus park job and a scoreless draw. That would benefit nobody. Liverpool need a result and United need a performance.

Something’s got to give.

IT was fine and dandy when Chinese clubs were coming for benchwarmers (Oscar, Ramires) and old guys with big wages (Didier Drogba, Nicolas Anelka). But this Diego Costa business is a bit of a game-changer.

The Spaniard fell out with manager Antonio Conte, ostensibly over treatment for a bad back, though the back pages are full of talk of an £80 million bid from Tianjin Quanjian, newly promoted to the Chinese Super League. The fact that super agent Jorge Mendes met, very publicly, officials from the Chinese club only adds fuel to the fire, as do stories of £500,000-a-week pay packets.

It may be, as some have suggested, that this is a classic contract play. Costa enters the final two years of his contract at the end of the season and the club have been trying to negotiate an extension that would pay him some £200,000 a week. And maybe the Chinese offer is imaginary, but real enough to make Chelsea think just how much others value Costa. And his bad back could be a way of reminding the Blues just how difficult life is without him.

All speculation, of course. And if that’s what it is, fine. But if we’re in a situation where a Chinese club can walk into the middle of a Premier League season and force a move for the league’s top scorer at a time when his club are top of the table, then we really do live in a brave new world.

ON the subject of unhappy players with bad backs, Dimitri Payet has attracted all sorts of bile after telling the club he wants a move and threatening to down tools if he doesn’t get one. Coming less than a year after signing an enormous new contract, the usual excuse (“my family haven’t settled”) doesn’t really fly. And so Payet gets the greedy mercenary tag.

Which isn’t entirely fair. Because however much out of order and unprofessional his behaviour may be, greed really does not seem to come into it. Marseille’s offer would see him take a hefty pay cut over his current £120,000-a-week package.

Of course, that would spoil the greedy foreign mercenary narrative.