The fact that the visit of Real Madrid to Wembley represents Alli's entrance onto the Champions League stage this season is a direct result of the negative side of his game overshadowing the positive on his last appearance in European competition for Spurs.

Alli was hit with a three-match suspension by UEFA for a wild and reckless challenge on Gent midfielder Brecht Dejaegere, which earned the Spurs man a red card during the 3-2 Europa League defeat against the Belgian side in February. He's certainly had to suffer his punishment this term as Mauricio Pochettino's team have made an impressive, unbeaten start to their campaign in Group H.

The big question is whether his enforced spell on the sidelines has helped Alli to fully grasp the consequences that follow when he allows the ugly side of his game to overshadow his many positives. His recent behaviour on the pitch for Tottenham and England would suggest that such lessons have yet to be learned, judging by the one-match ban he received from FIFA for the obscene gesture apparently directed at teammate Kyle Walker during the World Cup qualifier against Slovakia in September.

As recently as Saturday, Alli was accused of diving following a Phil Jones challenge and then allowed himself to be dragged into a verbal spat with Manchester United's Ashley Young during Tottenham's 1-0 defeat at Old Trafford, when his focus was quickly distracted by a set of opponents prepared to target him in an attempt to ruffle his feathers.

United's approach worked and it will be a cause for concern for Pochettino, who has already criticised Alli publicly this season for attempting to deceive a referee by diving during the Premier League win at Huddersfield in September.

"This type of action doesn't help him, doesn't help the team and doesn't help football," said Pochettino. "We are talking in the last few years about fair play. I think he is improving a lot and learning, but still he must learn."

There are some who will argue that the flaws in Alli's character are simply part of the package and that without his readiness to play on the edge, it would nullify his impact and contribution. The same excuses were often made for David Beckham and Wayne Rooney, two of Alli's predecessors in the role of "English football's golden boy," but both were ultimately successful in eradicating their impetuosity.

They were both in their early 20s when the penny began to drop, too, so Alli can at least point to his age and plead for the time to develop the maturity that he currently lacks. However, another more difficult reality for the Spurs player is that Beckham and Rooney, and others like Paul Scholes and Steven Gerrard, were delivering on the big stage at a time when their temperament was being questioned. For all of his talent, Alli has yet to produce the kind of performance that Beckham, Rooney, Scholes and Gerrard had delivered for club and country by the age of 21.

All of the above had won major trophies by that point in their careers and had performed with distinction in Europe and for England, but Alli's reputation currently exceeds his achievements, and he is now approaching an age when he has to live up to the hype.

Such hype is justified because the former MK Dons midfielder has made a huge impact in the two full seasons he has had at the top level since arriving at Tottenham for just £5 million in the summer of 2015. He has scored 31 goals in 80 league games and become an England regular, although his strike-rate on the international stage is a less impressive two goals in 22 appearances.

With Spurs, Alli has showcased an ability to score regularly from midfield and also contribute goals for others, most notably Harry Kane. But his encounter with Real Madrid will see Alli measured against the very best and gives him the perfect opportunity to show that he really can take his game to the next level. Right now, that question mark remains because his disciplinary record shows no sign of improvement and he has yet to produce the kind of performances capable of dragging Spurs to silverware and glory.

The game against Real could be the one that sees Alli make the big stage transition from boy to man, a night when he announces himself to the world against the best team on the planet. But we might well see the boy again: the kid with all the talent, but not enough of the sense and discipline to make the most of it.