Yury Gazinsky got the party started at the Luzhniki Stadium in the 18th minute with a smart header. Denis Cheryshev struck twice off the bench, and Artem Dzyuba and Aleksandr Golovin each bagged goals to seal the comprehensive victory.
Golovin was the star of Thursday's curtain-raiser, setting up two of Russia's goals while chasing down every loose ball. It was easy to see why the tricky CSKA Moscow midfielder is drawing interest from some of Europe's top clubs.
The stats show that the Saudis controlled the majority of possession, but it didn't matter. They failed to register a single shot on target, leaving Russian 'keeper Igor Akinfeev with little to do.
Few expected Russia to do much damage in the World Cup, with The Moscow Times branding the national team "aging and inexperienced."
But these 90 minutes told a different story. Even after losing talisman Alan Dzagoev to injury early in the first half, there was a lot of individual talent on display. Golovin's movement was sublime, and Villarreal forward Cheryshev was brimming with confidence. His second goal was brilliant, smacked perfectly with the outside of his boot to beat Saudi Arabia's diving goalkeeper.
Russia's next match is against Egypt on Tuesday.