Chelsea are free-falling, Liverpool are in transition and Manchester United do not quite seem to know what they want to be. If ever there was a chance for Tottenham to step in and crack the top four, it would appear to be this season.

They are unbeaten in the Premier League since the opening day of the campaign, have a solid defence, a brilliant goalkeeper and an attractive attack. It is a young team of surprise packages and swagger, which increasingly appears to have mastered Mauricio Pochettino’s plans for high pressing and quick passing after some disjointed attempts last season.

But against all that, it is also a team that has to juggle their domestic assignments with Europa League football. Not many clubs pull off the trick. So, can they do it?

Here, Sportsmail looks at five reasons why Tottenham have done so well this season and considers why this might just be time for them to take the next step.

Harry Kane (left) and Erik Lamela celebrate combining for Tottenham's third goal in their win over Aston Villa

Spurs appear to have mastered Mauricio Pochettino’s plan for a high-pressing and quick-passing game

THE REVELATIONS

Has another side in the Premier League had so many pleasant surprises this season? Tottenham were able to survive Harry Kane’s lean spell because other areas of the team were so effective – and they were areas of success that few could have anticipated.

Dele Alli is the standout name, having arrived from MK Dons. Jan Vertonghen was honest enough on Monday evening to admit he had never heard of Alli before he rocked up at Hotspur Way.

Vertonghen said: ‘To be honest, before he came here, I didn't really know him. Nothing bad about that - I don't know anything about lower leagues. But you think I mean this in a bad way but this guy has impressed everyone since the first day we met.’

Alli’s performances as a deep-lying midfielder have incredibly led to two England caps at 19. Alongside him, and equally as impressive, has been Eric Dier. He has journeyed around right back and central defence, but as a defensively-minded midfielder this season has been exceptional. The combined age of that Dier-Alli axis is only 40.

Beyond that pairing, Erik Lamela has suddenly stirred. His reputation has shifted from that of a £30million flop to a player who can change games. He has been excellent, scoring twice and creating three more in the Premier League. Along with Christian Eriksen, he offers the creative power to keep Tottenham winning games.

England midfielder Dele Alli has been a revelation for Spurs since his step up from MK Dons this season

Defensive midfielder Eric Dier (right), who with Alli makes a combined age of 40, has also impressed

THE BACKLINE

Tottenham have conceded only nine league goals this season – jointly the third best tally in the division - and a significant element of that is down to the pairing of Toby Alderweireld and Vertonghen.

Between them, they have not missed a minute of Premier League football so far. Considering every other player in the squad has been taken off or rested at some point or other, it would indicate how important they are to Pochettino. Certainly the pairing has strengthened as a result.

As a pair of big men, they also add strength and experience to a team that likes to be light on its toes. Across the Premier League, only Sebastien Bassong and Russell Martin have a higher combined number of headed clearances (122) than Vertonghen and Alderweireld (84).

A key aspect of this campaign will be how Pochettino manages his resources across domestic and Europa League assignments. He has already shown a willingness to rotate Danny Rose and Ben Davies at left back for continental games, while Kieran Trippier has also been used in place of Kyle Walker in the Europa League, where Spurs have looked less sturdy.

Domestically, though, the unit has been strong. Dier is a big element of that, with the defensive base balancing the five attack-minded players that Pochettino tends to deploy. It helps that Hugo Lloris is one of the best goalkeepers in Europe.

Jan Vertonghen (left) and Toby Alderweireld (below right) have played every Premier League minute so far

The Belgian centre-back partnership has been strengthened by regular game time and faith from the manager

KANE IS ABLE

Harry Kane was always going to suffer close scrutiny after his breakthrough last season, but it is worth noting that while his scoring was slow to gain momentum, he was not playing badly. The fact Tottenham lost only a single game in the dry patch is not only testament to the other players, but also an encouraging sign. If they could make progress up the table when Kane was not scoring, what will they do now that he is?

Such hypotheticals don’t always play out, but after scoring against Villa, having hit a hat-trick at Bournemouth a week earlier, he now appears to be in good form. With five goals for the season, a hefty element of the numerical pressure is off as well.

Concern will come from the heavy strapping he has recently worn on his knee, as Tottenham are worryingly light on strikers.

Spurs won without Harry Kane not scoring but now he's back in the goals who knows what can happen

THE WIZARD

Christian Eriksen is the creative master of the side. While Kane took the credit last season and the emergence of Dier and Alli have drawn attention this time round, it is Eriksen who consistently delivers match-winning performances.

He is an exceptional player, an attacking midfielder who not only spots and executes the passes through tight spaces, but who also hits free-kicks as well as any player in the division. His performance at Bournemouth recently was simply exceptional.

In all, he has created 25 chances and had three assists. Aged only 23, like Lamela, he is another example of a deeply talented Tottenham player with time on his side. There are still questions about how frequently he can dominate the big games, but there cannot be many contenders out there who would not want him in their side.

Christian Eriksen is Spurs' undoubted creative master who consistently delivers match-winning performances

Another creative power is Erik Lamela, who has gone from being derided as a flop to a game-changer

NO MORE CHOKING

Tottenham have long been the soft touch that wilts against their direct rivals in the table. That psychological sense of inferiority has been discussed at length by Pochettino and Lloris in the past and it is only by beating the established giants that a change can be made.

The 4-1 demolition of Manchester City felt like a major moment for this squad, which is now demonstrating an ever clearer understanding of Pochettino’s system.

This month, when Tottenham play Arsenal and Chelsea immediately after Europa League fixtures, will offer a major indicator of how they are developing on this front.

…BUT A NOTE OF CAUTION

As mentioned, Tottenham are perilously thin up front. A shortcoming of their transfer window operations was that they started the season with only Kane and Heung-min Son as recognised strikers. Son’s lingering foot injury has highlighted the shortcoming of that approach, interrupting his impressive start to life at Spurs.

Clinton N'Jie frequently played as a second striker in France, but still looks too lightweight to play up front on his own. He has more often been used out wide. An injury to Kane, therefore, could have a devastating effect.