Comment: Alli and Spurs need to grow up in a hurry
Chelsea clash provides a chance for faltering star to shine and get firmly back in Southgate's plans
For 28 years Spurs have made winning at Stamford Bridge seem about as feasible as scaling Mont Blanc in beach shoes, but on Sunday they had better take the grappling irons and the ice picks.
They must regain their footing; that confidence that comes to a seriously proven team and for no one is the need more pressing than the recently-fabled young superstar Dele Alli.
It is a challenge that permits a succinct enough definition. Like his team, Alli - 22 in a few days - needs to grow up.
In some of the wider aspects of life George Best never quite managed that but, as a footballer, he was all of one brilliant, nerveless piece when he arrived at the birthday that now requires Alli to take a long and penetrating look at himself.
At almost precisely this age, Best was the star of Manchester United's 1968 European Cup victory over Benfica and was voted Europe's player of the year over the claims of such as Eusebio, Franz Beckenbauer and Bobby Charlton.
An ancient perspective, you might say, but only when you ignore the fact that the development of the greatest players follows an eternal pattern.
The talent comes in the cradle, the achievement in the understanding of what you have been given and how best you can develop it.
Currently, and after the brightest of starts which made some believe he was heading for the stratosphere occupied by the small elite of today's game, Alli is scarcely displaying a clue as to how he might, along with Spurs, regain lost momentum.
The last week of international friendlies has seen his stock sink faster than Facebook shares, a convulsion which has come three months into a year which has brought fast-accumulating questions about his ability to deal with a crisis of both confidence and commitment.
England coach Gareth Southgate still insists Alli remains an "important player" in his World Cup plans but it is an assertion which is strained, to say the least, by the fact that he has slipped behind not only the intensely Guardiola-groomed Raheem Sterling but such lesser natural talents as Jesse Lingard, sharp and energetic, and the hard-working but slow-to-thrill Alex Oxlade-Chamberlain.
Alli last started for England in a World Cup qualifier against Lithuania and has scored just two goals for Spurs since the turn of the year.
Significantly, while he was musing on the bench over an uncertain future, Lingard was scoring against Holland and supplying a quick-witted assist in the Italian game at Wembley. It underlined the fact that, during the Alli malaise, Lingard has appeared four times for England and scored five for Manchester United.
Admirers of Alli's talent, his phantom-like ability to change pace and direction under the tightest pressure, will make the point that in the last few years he has, at times, brilliantly put behind him the dislocations of a broken family and a battle for personal identity. But then they will avoid the fact that some of the most superb football careers were not exactly marked by serene boyhood.
Best's youth in Belfast was hardly carefree, Cristiano Ronaldo lost his alcoholic father at 20 and Diego Maradona's worst childhood memory is being rescued from the cesspit next to his family's shack in the shanty town where he grew up.
Alli has, in so many ways, pulled off the hard part. He has announced himself as a player of highly uncommon instinctive brilliance. At his best, he provides the exhilaration of a thoroughbred streaming for the winning post.
So, what's the problem? It is one that ultimately is beyond the powers of Southgate or Tottenham's notably persuasive manager Mauricio Pochettino. It is about Alli's ability to grasp where he has gone wrong.
After the humiliation of England's defeat by Iceland in the European Championships of 2016, Alli swore that he and his team-mates would grow stronger at the broken place. He said, as he lay on the pitch, that he would never stop learning from the meaning of such a shocking defeat.
He would work harder, re-assess his priorities. Unfortunately, the record does not support such a passionate resolve.
Before the Icelandic disaster he had missed Tottenham's excruciatingly ill-disciplined draw at Chelsea two years ago - when a 2-0 lead was thrown away and nine yellow cards were received - through a three-match suspension for striking an opponent.
His absence, given the riot of wild behaviour by his team-mates on the field, may or may not have significantly affected the draw which waved Leicester through to the title and denied Tottenham their best chance so far of gracing Pochettino's impressive regime with a major trophy. What he did do, though, was mark a point at which the certainties of a dazzling 20-year-old were first cast into doubt.
The questions have certainly compounded since that first serious flashpoint. He has served bans in England and Europe, been accused of a potentially dangerous tackle on Manchester City's Kevin de Bruyne, disciplined by Fifa for showing the finger, has a rash of yellow cards for simulation and, in the psychologically-crushing Champions League defeat by Juventus, he mixed into some brilliant touches a preposterous dive, a booking, and was withdrawn a few minutes before the end of the drama.
This, plainly, is not some seamless passage towards the greatest football distinction. Indeed, redemption for both Alli and Spurs is a basic need at Stamford Bridge. Both the player and the team are charged with a failure of competitive maturity and we can be sure Antonio Conte's Chelsea will be hell-bent on producing more evidence for the prosecution.
In that yielding of the title two years ago, Spurs suffered gravely from the pressure of a Chelsea managed by the knowing old football man Guus Hiddink and the presence of the inflammatory Diego Costa, who of course might have brought discord to the Last Supper.
Defeat would not only imperil Tottenham's chances of returning to Champions League football but question the ability of Pochettino, for all his talents, to deliver something closer to a finished product. For Dele Alli the challenge is more basic. He has to prove much sooner than he could have imagined that he is quite the player so many still believe him to be.