Switzerland coach Ottmar Hitzfeld has put the number of World Cup first-round shocks down to the fear of failure.

The Swiss pulled off arguably the result of the tournament to date when they defeated reigning European champions Spain 1-0 in their opening Group H match, but there have been plenty of other surprises.

"The favourites have a lot of pressure because everybody just takes it for granted that they will reach the round of 16," said Hitzfeld. "There is the fear of failure and if you struggle, you become nervous, and that's when the underdogs have an opportunity to create a surprise."