After portugese discovery of the Moluccas (Molukken), the Spanish began to have doubts about the treaty: Possible to sail west and reach the Islands from the other side? Then the Moluccas would be Spanish possession!
Portugese navigaton 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.