Alli has been a revelation since arriving at White Hart Lane from Milton Keynes Dons, and he has impressed Thompson with his performances.
The 19-year-old has been stationed alongside Eric Dier in the heart of Spurs' midfield, and Thompson feels that Alli's attacking intent has given Tottenham something they have been missing for a long time.
"He's impacting on the game," the former Liverpool player said. "He's saying now, 'I belong in this league. I belong in this team'.
"Spurs normally have two holding midfielder players who pass square. Eric Dier, who has done very well, Ryan Mason and Nabil Bentaleb are all very alike. Dele Alli has got something different for this Spurs side. You have got flair players in front of him, but you need something different."
Alli arrived at Spurs as a hot prospect, but he has quickly established his position in the starting line-up, and is now playing a key role for Mauricio Pochettino's side.
The powerful midfielder has arguably been Spurs' most consistent performer so far this term, with his performances catching the eye of England boss Roy Hodgson.
The Three Lions have called Alli into their squad for upcoming Euro 2016 qualifiers against Lithuania and Estonia, and he could be in line to make his first appearance for his country in the coming week.
If Alli does play for England, it will cap off a remarkable rise, and Spurs fans will hope that the hype around him at present doesn't impact negatively on his progression.