|Kaka scored his goal for the 'Merengues'|
Ronaldo opened the scoring early on after converting Mesut Ozil's pass and defender Marcelo added a second to give the visitors a comfortable advantage at the break.
The second half was all one-way traffic as Ronaldo helped himself to two more from close range, while Xabi Alonso and Kaka chipped in with superb long- range strikes, as Jose Mourinho's men sounded an early warning to champions Barcelona, who begin the defense of their title at Villarreal on Monday evening.
"At 2-0 the game was already over and so it depended on whether we played together or individually and the players chose the first option so we won by a big margin," Mourinho told reporters.
Zaragoza (0): Roberto Gago, Paulo da Silva, Fernando Meira, Paredes, Efraín Juárez, Zuculini (53' Ádam Pintér), Ponzio, Uche, Lafita, Abraham Minero (53' Edu Oriol), Pablo Barrera (82' Joel Valencia)
Real Madrid (6): Casillas, Carvalho, Pepe, Marcelo, Sergio Ramos, Coentrão, Xabi Alonso, Benzema (76' Higuain), Özil (78' Kaka), Ronaldo, Di María (72' Callejón)
Goal Scorers: Ronaldo (24' 0-1), Marcelo (28' 0-2), Xabi Alonso (64' 0-3), Ronaldo (71' 0-4), Kaka (82' 0-5), Ronaldo (87' 0-6)