Last season, Harry Kane was the man of the moment. His remarkable goalscoring return of 31 goals in 51 games made him a phenomenon.
A virtual tidal wave of memes was created around Kane's exploits and unleashed every time he added to his tally. He was the poster boy of Tottenham Hotspur's season in 2014-15 because, aside from his individual achievements, the team weren't that good.
In Mauricio Pochettino's first season, they were usually solid, occasionally good and often lucky. They finished fifth in the league but never seemed likely to break into the top four.
This season, Spurs have mutated into something closer to Pochettino's ideals, and the team and manager are reaping the rewards together.
Sitting fourth, they are equidistant from fifth place and first (five points). They are a significantly better side this season and part of that comes down to the rapid development of Dele Alli.
Alli is most often deployed as part of the three-man attacking midfield line that Pochettino deploys in support of his main striker. Occasionally stationed wide on the left but usually through the middle, this is the 19-year-old's ideal position.
The importance of that attacking line in Pochettino's pressing game makes this a hugely demanding role to play, but Alli's incredible endurance makes him better suited than most.
Where Pochettino essentially deploys his team in a 4-2-3-1 formation, Alli's capacity for hard work and ability to drop into the defensive midfield line when required makes it seem as if Spurs are playing a 4-3-3-1.
Pochettino's system, and aggressive pressing generally, is constructed around the ability to create numerical superiority around the ball.
Alli makes that system work better and faster than any of his team-mates. The defensive side of the game is a huge part of the teenager's value to this team. It was his ultra-aggressive press that set Spurs away for the opening goal against Watford.
The pressing game is more complicated than simply charging at the man on the ball, but Alli appears to have absorbed Pochettino's instructions quickly and is an able exponent of the system.
Once Spurs have the ball though, Alli truly begins to shine. A thoroughly modern midfielder, the former MK Dons man is quick and clever with his movement, skillful with the ball at his feet and physically impressive despite his youth.
He is often compared with Steven Gerrard for the energy he brings to Tottenham's midfield, but Alli also possesses some of the great qualities of the Liverpool legend's former England team-mate Frank Lampard.
An innate sense of timing—knowing exactly when to arrive on the edge of the box—was part of what made Lampard a legend. Alli seems to have the same level of awareness.
To bring a sense of context to Alli's achievements so far, Lampard was yet to score a goal in professional football at the same age.
Alli is scoring at roughly the same rate he managed during his MK Dons career. He has six Premier League goals for Spurs at a rate of 0.28 goals per game against the 22 he managed for his former club at 0.29.
Few could have thought that a star and regular goalscorer for MK Dons in League One would transition to the Premier League so easily.
Like many truly great players, Alli's goals seem to come from him deciding it is time to leave his mark.
Against Southampton, Leicester City, Everton and West Bromwich Albion, he scored as the lone man in the opposition box, breaking beyond his team-mates as if having consciously determined that this was his moment.
Lionel Messi often appears to simply be playing park football on the world's biggest stage. He has played the same way for his entire career, never having lost the uniquely childlike approach to the game.
Alli's goal against Crystal Palace evoked the same feeling. As if playing with his friends—not in a must-win Premier League match—the teenager controlled Christian Eriksen's header, lifted it over the onrushing defender and volleyed it into the bottom corner.
That goal, as much as any of his clever touches, exciting runs or delightful nutmegs, showed why Alli is Spurs' X-factor.
Manchester United have the money and if they had the sense they would move heaven and earth to acquire Alli in the current transfer window. Not since Wayne Rooney has a teenager so significantly influenced a title challenge.
Without Alli, Tottenham are a good side. They might probably still be favourites for the top four and more likely title contenders than United.
With the youngster, though, Spurs are a legitimate title threat and comfortably favoured to claim one of the four Champions League spots.
Alli's energy creates numerical overloads up and down the pitch while fearlessness of youth makes him willing to attempt the sombrero-volley.
He is a unique player and one of the main reasons why Tottenham are in the title race.