After the Portuguese discovery of the Moluccas (Molukken), the Spanish began to doubt the treaty: is it Possible to sail west and reach the Islands from the other side? Then the Moluccas would be Spanish possession!
Portuguese navigation Ferdinand Mallegan sailed from Seville and tried in order of German/Spanish king Charles V (Karel V).
Mallegans' journey took him around the world. Magellan himself didn't survive the journey as he was killed.