Borussia Dortmund is reportedly among the European powerhouses showing interest in Kostoulas, with sources indicating to CaughtOffside that the club has a strong interest in the 17-year-old Olympiacos wonderkid forward. Kostoulas, who is in high demand by several top European clubs such as Bayern Munich, Juventus, and AC Milan, has been valued at €30m by Olympiacos. Although Olympiacos is hesitant to sell, the attention from these prominent clubs underscores Kostoulas's potential and suggests that a move to a larger club is likely in the near future.