Kulusevski has not played a competitive minute this season after undergoing knee surgery in May 2025.
He disclosed ahead of Sweden's World Cup play-off campaign that he required a second procedure, though expressed confidence about being available for the tournament in North America this summer.
De Zerbi, speaking at a press conference, was measured about the timeline but fulsome in his praise.
"I feel sorry for him because he was one of my perfect players. He is a very specific player for me, like Kudus, like Romero. I hope that he can play in the World Cup, because the World Cup is a moment for a player. It is the best period in his career. But I don't know the situation particularly well," the Italian said.
Kulusevski has made 146 appearances for Tottenham since joining from Juventus in January 2022, contributing 25 goals and 30 assists.
He has been one of the club's most consistent players in that time and his absence has been a significant factor in their relegation battle, with Tottenham currently in 18th place in the Premier League.