Why did magellan approach the king of spain?

The cost of an expendetion was too much for a private person to Afford, so the support of a royal coffer was required .As a Portuguese Man, Magellan first sought the support of the Portuguese monarchs. However since Magellan wanted to sell westwald to find Asia ,Portugal was disinterested in this as they had already found a route around Africa.As a result Magellan petitioned the Spanish monarchs since they were more interested in West going routes