The action-packed forward has played an important role in managing Ange Postecoglou's system.
However, MilanLive suggests Spurs may have to fight to convince Kulusevski to stay next season.
If Milan can move up Samuel Chukwueze, they will make their move for the winger.
The deal will most likely take place in the summer, but a winter change cannot be ruled out.
Spurs want at least £41 million for Kulusevski, while Milan want a loan with an obligation to buy.
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