Buddha's night before enlightenment

According to the historical story before the day of enlightenment, Mara apparently lured the Buddha with various worldy pleasures. Now, I am not arguing whether Mara really existed or is just Buddha's mind (which would be rather my interpretation). But The Buddha should at that time be a non-returner and he must have abandoned the fetter of sensuous desires. He should've chilled in the 4th Jhana not giving a damn! So my question is: Why was it a struggle for the Buddha if the conditioned fetter of sensuous desire was already uprooted as an anagami?