There is an awkwardness to the situation in which Tottenham find themselves, a hollowness that should reverberate around all of modern football. Over the past three seasons they have probably been the best side in the Premier League. They have improved each year under Mauricio Pochettino. Their squad is perhaps better than ever before, certainly than it has been for half a century. They are a young, developing side, with an impressive young manager. They play progressive, modern football. They can press high or sit off and look to play on the break. And yet everything they do exists in a vacuum of impossibility; success a staging post to a destination that may lie for ever out of reach.

Once they had found their equaliser at Newport, last week could not have gone much better for Tottenham. Not only did they beat Manchester United but two of their top-six rivals slipped to surprising defeats. The gap from Spurs in fifth to United in second could have been 11 points; instead it is five, while Arsenal are six behind. Having broken the jinx last season, those days when Spurs finished behind their neighbours look to have been consigned to history.

This has been a memorable season. They have taken four points off Real Madrid and six off Borussia Dortmund in the Champions League. They have outplayed Manchester United at home. They are averaging almost two goals a game. Twenty years ago, their average of a fraction under two points per game would have had them in the thick of the title race. This season they are 20 points adrift and, for all that has gone right, they risk missing out on Champions League qualification.

Their position is precarious. Without Champions League football, how many of this squad might consider their options? As Danny Rose made clear in the summer, the players are very aware that they could follow Kyle Walker in leaving the club to double their money elsewhere. Without the revenue of Champions League football, it will be all the harder for Tottenham to offer the pay rises that might placate those whose heads are turned. Without Champions League football, how easy will it be to maintain the belief this is a project worth sticking with?

That question should concern everybody involved in football. Tottenham have done just about everything right. They have not overspent. They have developed talent they either bought young or produced themselves. They have sought to increase revenues with investment in infrastructure. If football is not merely to be the propaganda wing of petro-inflated billionaires, that must be the model clubs are encouraged to follow. Fans used to dream of salvation through a great generation of young players or a messianic manager; now advancement comes by catching the eye of a passing oligarch or sheikh.

‘Everything they do exists in a vacuum of impossibility.’ Photograph: Facundo Arrizabalaga/EPA

Yet Tottenham exist constantly in earshot of a ticking clock, of players and perhaps a manager who cannot be expected to resist the lure of greater financial rewards for ever. Perhaps the fleetingness of the moment enhances its appeal but from a pragmatic point of view the best they can hope for is that this generation is raising funds and the club’s profile for a title challenge in a few years’ time, when Manchester City are no longer elevated by the combination of Abu Dhabi’s wealth and Pep Guardiola’s genius.

Liverpool’s situation is not entirely dissimilar, although they are far less constrained by a rigid wage structure. Both sides are capable of hammering opponents. Get a lead, and they can tear sides apart with rapid counters. But a major doubt remains about both. For Liverpool, it is the sense that once an opponent gets beyond the press there is a profound fragility. The signing of Virgil van Dijk may help remedy that vulnerability but, as West Brom proved, it has not erased it.

For Tottenham, the flaw is an occasional flatness. That may in part this season have been caused by their evolution into a more flexible side, one that does not need to dominate possession to dominate games and occasionally struggles, particularly against lesser sides, to get the balance right. But it is also down to a reliance on Christian Eriksen, a problem exacerbated by Dele Alli’s suspect form this season and Moussa Sissoko’s unreliability.

The Dane has missed only seven games this season: two straightforward Champions League wins over Apoel and an FA Cup victory over AFC Wimbledon, but there has also been a grim 1-0 win over Barnsley in the Carabao Cup, defeat by West Ham in the same competition and draws against Southampton and Newport. When Eriksen is not there, Spurs look short of creative flair. The return from injury of Érik Lamela and the signing of Lucas Moura should ease that, but the dependence is at least in part an issue of a lack of squad depth.

Eriksen is back and Liverpool’s high press means his capacity to unlock massed defences is anyway less likely to be relevant on Sunday, but the feeling that none of it really matters, nags that this is all a fantasy of jam tomorrow. Spurs have to glance four miles to the south to see those dreams can be sustained only for so long.