Alli has been called up to the England squad for the first time for their fixtures against Estonia and Lithuania in the coming week, and he seems to have made a positive initial impression.
Hart is one of the players to have been impressed by the 19-year-old, and he has backed Roy Hodgson's decision to draft the Spurs youngster into the senior side, despite a lack of experience.
"He's really pushed on," Hart said. "He had a good season last season, and Tottenham have put him into a very good side. It's good to get him in. He's someone who will be in the England side for a long time."
Alli has only played seven times in the Premier League in his entire career, but his form made it impossible for Hodgson to ignore him.
The versatile midfielder has played in front of his side's defence and behind the striker so far this term, and has excelled in both roles.
Alli is comfortable in possession, but he also has a physique which belies his tender years and has coped admirably with the demands of playing top-level football.
Alli's arrival at Spurs has added to the excitement about their current squad's future, with Mauricio Pochettino having some of the most talented youngsters in the country at his disposal.