Is this a save situation?

if the yankee win 10-0 and they get all of the runs in the 4 inninng and the yankees pitcher pitches until the 7th, and then mariano rivera pitches the 7th, 8th, and 9th, is it a save? my dad denies that it would be but i say it would be a save. my dad doesnt trust wikipedia so i need some real sources to prove it