Tottenham take on the Italian club later in the week in the first leg of their Champions League encounter, with both sides fifth in their respective tables after indifferent runs of form.
Leao has continued to excel at AC Milan this season and in the group stage of the Champions League, he started every match and contributed with three assists along with one goal.
Antonini feels that while Olivier Giroud is an important member of the AC Milan squad, the most fundamental player in their team against Tottenham will be Leao.
The former AC Milan left-back complemented the Portuguese star on his game-changing abilities and stressed that Leao would be his first pick currently from the team.
Speaking to Italian daily Tuttosport, Antonini said: “The Frenchman [Giroud] has shown once again that he is an all-round champion.
“He is an important man for the Milan dressing room, he is a player who, like Ibra, feels like one of those who raises the bar for his team-mates.
“But against Tottenham Leao will be fundamental, he is the top player of this team.
“Even if he is not at his best, he remains a fundamental player, the wild card who can turn the game round on its head.
“I would have no doubts, I would always play with Leao plus ten others.”
AC Milan failed to score and let in five goals the two times they faced Premier League opposition this season, against Chelsea, and Tottenham will be hoping for similar in their last 16 clash.
