Eternal rivals Barcelona may have lost Lionel Messi but Real themselves are in a period of transition having seen Zinedine Zidane step down as coach and central defensive linchpins Sergio Ramos and Raphael Varane head for Messi's PSG and Manchester United respectively.
Even with their big names still on board both of Spain's biggest clubs were unable to prevent Atletico Madrid walking off with the title last season.
But after initially failing to click in a goalless first half, Real found their rhythm after the restart as the returning Gareth Bale found Eden Hazard who flicked on with his heel for Benzema, skipper in the injured Marcelo's absence, to volley home on 48 minutes.
Bale blotted his copybook with a booking for a high boot thereafter but Real -- who featured their only new face in David Alaba -- did not allow that to loosen the grip they were steadily taking on the game.
Nacho volleyed in from close range following a Luka Modric short corner on 56 minutes and Benzema made it 3-0 and essentially game over just after the hour, scuffing in at the second time of asking after a fine run and assist by Federico Valverde.
A Joselu penalty for the hosts was a minor blemish after Thibaut Courtois, making his 100th Liga appearance between the posts for Real, brought down John Guidetti.
But a Vinicius header applied extra gloss for Real's fourth in injury time.
In other action Saturday, Cadiz and Levante parted 1-1 as did Mallorca and Real Betis while the match bewteen Osasuna and Espanyol ended in a goalless stalemate.
Atletico start their title defence Sunday at Celta Vigo in Galicia while Barcelona begin the post-Messi era at the Camp Nou against Real Sociedad while Sevilla host Rayo Vallecano.
There are two matches on Monday as Villarreal go up against Granada while Elche meet Athletic Bilbao.
Valencia got the ball rolling Friday and pocketed three points after an early Carlos Soler penalty was enough to see them overcome Getafe 1-0.