The 21-year-old has scored 16 Premier League goals for Tottenham this season, and just 12 months after picking up the same award last season, Alli is favourite once again ahead of Sunday's ceremony.
Alli has grown as a player and character over the past year, and here's how...
Ask 100 people to sum up Alli in one word and you may well get 100 different answers.
This season, Alli has displayed more layers to his game and character; versatility, maturity on and off the ball and different goals, but all with the same unflagging energy.
His two headers against Chelsea, the sweeping finish against Manchester City and the long-range pearler against Watford showed the variety of goals in his armoury, but beneath that Alli's all-round game has improved and expanded.
Alli does not rely on one trait. He is the epitome of an all-round player, and though comparisons to Steven Gerrard, Paul Gascoigne and Frank Lampard were inevitable, none seem appropriate.
"Maybe one day he plays as a goalkeeper, full-back or centre back," Mauricio Pochettino said earlier this season. "Dele Alli can always surprise you. He has an unbelievable personality and character. Anything is possible for him."
In Alli's first half-a-dozen Tottenham games in 2015, we saw a 19-year-old with greenness and promise in equal measure.
In that opening period, one game stood out. During his first match in central midfield, a 1-0 win over Crystal Palace at White Hart Lane in September, we saw a one step forward, one step back Alli, getting a little too excited positionally while still having an impact on the game.
Fast forward 20 months, and Alli has already shaken off those raw habits, and Pochettino was correct to question is exclusion from the seniors PFA Player of the Year award shortlist.
Yes, he still has those "happy feet" on the ball, as Sky Sports pundit Niall Quinn once put it, but the 21-year-old's positional maturity and decision making belies his age.
Alli's goals came in spurts last season, but this year the strike-rate has been more consistent.
With 16 top flight goals, he needs four more this term to become only the third midfielder in Premier League history to reach 20 goals, in fine company alongside Frank Lampard and Yaya Toure.
But does the 'midfielder' tag still fit? Alli's role as second-striker, particularly in the absence of the injured Harry Kane throughout spring, has shown the youngster in a new light.
"In the box, he looks like a striker," said Pochettino in March. "And outside the box, he plays like a midfielder."
This season, Alli has proved that his ability to find space in the area is not dependent on his starting position, and that knack of ghosting around the final third into dangerous areas doesn't happen by accident.
Alli said in a recent interview with Sky Sports' Pat Davison: "Especially in the Premier League, defenders are really switched on, so you almost have to fool them (with your movement) into thinking you're doing something else."
The summer months prior to this season did not go according to plan for Alli. His ban for punching Claudio Yacob at the end of the 2015/16 campaign summed up Spurs' stumble in the Premier League title race.
Alli, along with other Spurs team-mates, took their end-of-season form to France with England, and the youngster was among those criticised for under-performing.
He may have taken a few weeks to dust himself down at the start of this season, but Alli's performances this year have been all the more impressive within the context of last summer.
Even this season, after his red card against Genk in February hampered Spurs' chances of progressing in the Europa League, Alli returned to score four goals in four games.
Alli has a fiery streak, of that there is no doubt, but he's proved this season he can bounce back. He'll be hoping this term ends with a team trophy, not just the personal silverware.
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