It was Croatia with the early threat when Ivan Rakitic, earning his 100th cap, shot wide off a mistake by Sergio Busquets on four minutes.
Spain’s first chance found Rodrigo trying to find the bottom corner from a cross by Isco, but Lovren Kalinic outstretched hands came to their rescue.
It was opening up at either ends at this point in time, with Luka Modric’s forward pass connected well with Vrsjalko to cross low for Ivan Perisic whose shot at goal was put off by Dani Carvajal’s deflection.
The Spaniards took the lead when Saul’s late run in-between two centre-backs allowed him to head in Carvajal’s diagonal delivery in the 23rd minute.
Being in a commanding position, La Roja took flight and increased their tally through a blistering strike from outside the box by Marco Asensio on 32 minutes.
Soon, it was three after Asensio made space out right, dropped shoulder to the left and took off with a left-footed strike that cracked the crossbar and the backside of Kalinic before finding the net.
At this point, the Croatians were all at sea and Rodrigo nearly added to their woes in added time but missed within a whisker.
The second half started pretty much the way the first ended, as Spain continued from their destruction act on the World Cup finalists.
Valencia hitmen Rodrigo outsprinted the defence after beating the offside trap to beat Kalinic with an easy finish in a one-on-one scenario on 50 minutes to make it 4-0.
Captain Sergio Ramos made it five later on with his trademark header from Asensio's corner kick after abysmal defending.
Thereafter, it was time for Luis Enrique to make his first change from the bench, as Atletico Madrid’s Rodrigo came on for Busquets.
Though the demolition didn’t end there despite taking complete ascendancy of the tie. Isco made it six after selling a dummy to his marker to blast into the roof of the net.
The changes on either end from the bench rung, with the tempo of the game fluctuating from time to time given the hosts utter dominance.
Neither side then managed to break through, not the least the Croats who bowed to the 2010 World champions on the back of their stunning exploits the past summer in Russia.
Spain found a few chances to add more salt to the wound, but settled for the astronomical triumph to send a stern warning to the rest of the World.
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