Not really. The concern was more about finding a water route through the new world. Portuguese outposts existed in the "spice islands" already, along with European presence in South Asia (not to mention the Arab traders). Magellan was privy to what could be called "classified" Portuguese maps before defecting to Spain. He had a very good hunch from those that a water route around South America existed, though he greatly underestimated the distance across the Pacific.

Source: Over the edge of the world, by Laurence Bergreen