Maybe it is those infernal vuvuzelas. Whatever it is, something about South Africa disagrees with Spanish footballers. They have only lost twice in 48 matches since November 2006, both times here.
Last summer, in the Confederations Cup, Spain unexpectedly lost to the United States. If that was a shock this was a thunderclap. Switzerland is famous for its mountains, its cheese, and its cuckoo clocks, but not its footballers.
Spain, as usual, monopolised possession but while goalkeeper Diego Benaglio made some decent saves his was not one of those once-in-lifetime performances, it did not need to be. The one time he was beaten, by Xabi Alonso's rasping 25-yard drive with 20 minutes left, it rattled off the crossbar.
At the other end Iker Casillas was hardly troubled, until an old-fashioned goalkeeping punt caused chaos after 52 minutes and Gelson Fernandes, once, not very memorably, of Manchester City, scored. It was out of the blue, but not a freak, for 22 minutes later Eren Derdiyok weaved his way past three defenders and hit the post.
"I'm not used to scoring goals so I was a bit surprised," said Fernandes. He added: "I don't think I appreciate right now what has happened, it is a special moment for the Swiss national team and the country. I probably won't realise until after my career."
Ottmar Hitzfeld, whose experience was inked through the Swiss display like legend written in a stick of rock, said: "I am very happy. We did not allow many chances. There was not a huge fire in our penalty area. We were not shaking, not trembling, that gave us confidence and made the Spaniards nervous. They are contenders, they had to win."
It was not hard to see why they are contenders. The bench included Pepe Reina, Cesc Fabregas and Fernando Torres. A case could be made for this trio being, respectively, the best goalkeeper, midfielder and forward in the Premier League. The Swiss starting XI included a trio of players who had failed to nail down a place in the English game: Fernandes, Reto Ziegler (ex-Spurs) and Philippe Senderos (ex-Arsenal, now having a try at Fulham).
They did, however, have Hitzfeld who has steered two clubs to Champions League success. "Der General" had his troops well marshalled: Two banks of four, and Derdiyok, the second striker, preventing Gerard Pique bringing the ball out of defence.
That still left Xavi Hernandes, Xabi Alonso, Andres Iniesta and David Silva to create the chances for Barcelona's new €40m striker, David Villa. That should be enough but Switzerland defended with intelligence, perseverance, discipline and, at times, ruggedness. Gokhan Inler committed three fouls in the opening 20 minutes, while Senderos and his centre-back partner Stephane Grichting also fell foul of Howard Webb. The various free-kicks came to naught, however. Switzerland were too dominant in the air, and when the Spanish went for a shot they were no more able to control the notorious World Cup ball than anyone else.
The first indication of how successfully the Swiss were frustrating Spain came after 21 minutes when Sergio Busquets, who has scored once in his senior career, attempted a shot from more than 20 yards. Benaglio gathered easily, as he did later efforts from Silva and Pique.
And then the incredible happened. Benaglio launched a long kick forward which found its way to Derdiyok. Casillas clattered him but Fernandes followed up and though Pique blocked his first shot he stabbed in at the second attempt. It would be stretching a point to suggest the stadium fell silent, but there was a sense of shock.
Thereafter a siege developed. Villa, Iniesta and Navas all spurned chances as did Torres who looked very rusty when he came on. Too often, however, Spain were forced wide, crossed, and saw the ball headed clear.
No team has won the World Cup after losing their opening game. "It is not a good sign but we must cope with the situation," said Vicente Del Bosque, Spain's coach. "We may not have shown our true personality, but we will in the next matches."
Spain (4-2-3-1): Casillas; Sergio Ramos, Pique, Puyol, Capdevila; Busquets (Navas, 61), Alonso; Silva (Torres, 61), Xavi, Iniesta (Pedro, 77); Villa.
Switzerland (4-4-1-1): Benaglio; Lichtsteiner, Senderos (Von Bergen, 35), Grichting, Ziegler; Barnetta (Eggimann, 90), Inler, Huggel, Fernandes; Derdiyok (Yakan, 79); Nkufo.
Referee H Webb (England).
Spain's biggest misses
17 min The first opening fell to Spain's right-back Sergio Ramos, who received the ball in space on the right before dragging his shot wastefully wide.
25min Andres Iniesta slipped a pass through to Gerard Pique, who cut inside his man before firing straight at goalkeeper Diego Benaglio.
45 min David Villa finally finds space in the box but opts to pass, chipping tamely across the face of goal.
70 min Former Liverpool midfielder Xabi Alonso smashes his shot against the crossbar from outside of the area.
63% Possession 37%
24 Shots 8
8 Shots on goal 3
12 Free Kicks 3
12 Corners 3
8 Fouls 18
593 Passes 278
459 Passes completed 160
Fans' Network: Rival supporters around Britain give their views
Manuel Sanda, 46, Wine Merchant in Stirling, originally from Boimorto in La Coruna. Interviewed by Dan Ross
What a disaster! All credit to the Swiss, though, they got their tactics spot on. They played a physical, defensive game, holding off us and absorbing our pressure. They may have been a little too physical - I felt Howard Webb was too lenient and that we had three good shouts for penalties. But I am not blaming the referee, because we were poor. We played too arrogantly, having a lot of possession but not playing with the directness, the urgency that was needed. We missed a few chances, but didn't threaten their goal as much as we should.
We got it wrong tactically, too. I would not have given Andres Iniesta all that time on the pitch. His fitness is still not right and I think he was pushed too much. Towards the end of the match, when we were behind, we got desperate and played high balls - crazy when you think how tall their defence is!
There is a lot of pressure now - we have to win, there is no tomorrow! We must move from being the team with 'disaster' written on the back of their shirts, to winning our next two matches. We have to finish top of the group to avoid Brazil!