Spain, the defending world champions, were devastated by Netherlands 5-1, exacting revenge from their loss in the 2010 World Cup Final in the opening game of Group B.
Spain's recent loss was considered to be the worst in record since its defeat in 1950 by Brazil 6-1.
Van Gaal's states that he was "stunned by the margin of victory," says an interview in Yahoo! Sports. 'To be quite honest, we did not expect it,'' he said. ''This has got to do with strategy and the dedication of the players to execute with conviction.''
Xabi Alonso gave Spain a lead from a penalty shot on the 27-minute mark, but was soon matched by Netherlands as van Persie goals a jaw-dropping header before half-time.
Soon, the Spaniards' defenses were overwhelmed by the Dutch during the second half, scoring four more goals to secure Netherlands' victory against the defending champions.
Netherlands took their lead during the 53-minute mark, with Robben delivering a goal past Casillas, seconded by de Vrij's strike in the 60-minute mark, giving Netherlands a two-point lead.
''They were better than us in the second half, you have to recognize that,'' Spain coach Vicente Del Bosque tells Yahoo! News. ''It's a delicate moment for us. We need to find solutions now.''
Spain's trademark tiki-taka style proved to be useless against Netherlands' agressive, excellent, and well-organized attacks.
"I did not expect that it would go this way, it could have been 6-1 or even more, and we had a very happy feeling," Dutch coach Louis van Gaal told reporters after the match, a CNN report says.