Germany and the Netherlands, two of the sides widely-tipped as potential Euro 2012 winners, suffered worrying friendly international defeats on Saturday.
Germany slumped to a shock 5-3 defeat in Switzerland while the Dutch were booed off in Amsterdam after surrendering a one-goal lead to lose 2-1 against Bulgaria.
Defending European and world champions Spain, however, showed off their impressive strength in depth when a second-string side defeated Serbia 2-0.
England, meanwhile, gave Roy Hodgson a winning start as new national coach with a hard-fought 1-0 win over Norway in Oslo.
Germany, who rested their eight-strong Bayern Munich contingent, suffered their first loss to Switzerland, who failed to qualify for Euro 2012, since 1956.
Joachim Loew's Germany qualified for Euro 2012 without losing a match, but they have now lost two friendlies in succession having been defeated 2-1 by France in February.
Their last friendly will be against Israel on May 31 before embarking on their Euro campaign against Portugal, Netherlands and Denmark in Group B.
Swiss striker Eren Derdiyok, who has just left Bayer Leverkusen for fellow German Bundesliga side Hoffenheim, grabbed a hat-trick in Basel with Andre Lichtsteiner and Admir Mehmedi also on target.
Mats Hummels, Andre Schuerrle and Marco Reus hit back for the Germans.
"We didn't expect a result like this and we cannot be satisfied by it," said Loew.
"After a lot of intensive training sessions, it's clear that we didn't concentrate enough and made a lot of mistakes. The team didn't function, we weren't good today."
Netherlands' 2-1 loss to Bulgaria came just four days after they were beaten 3-2 by Bayern Munich.
Robin van Persie had given the Dutch a 45th-minute lead but Bulgaria levelled four minutes into the second half with an Ivelin Popov penalty after a handball by Rafael van der Vaart.
Striker Ilijan Mizanski hit the winner in the second minute of injury time on a counter-attack.
Dutch fans were so frustrated that Bert van Marwijk's team were jeered off at the final whistle.
"The result is disappointing," admitted the coach. "We took a lot of risks at the end of the game and were caught on the counter-attack.
"But that's football and we need to learn the lessons."
Roy Hodgson made a winning start to his reign as England manager after an Ashley Young goal in the ninth minute gave his side a 1-0 victory over Norway in Oslo.
Hodgson, who only took over as the successor to Fabio Capello earlier this month, saw his experimental England side record their first win over Norway for 32 years.
With only four or five of Saturday's starting England XI likely to feature in their opening Euro 2012 game against France on June 11, Hodgson was given the opportunity to run the rule over several fringe members of his squad.
However despite an encouraging opening spell from striker Andy Carroll and another goal-scoring contribution from Young, there were few major English success stories in a low-key contest.
"It's a great start. I was concerned about fatigue creeping in and some players were feeling their muscles," said Hodgson. "They worked hard in training trying to impress me."
With Euro 2012 starting on June 8, Spain coach Vicente del Bosque fielded a host of fringe players with Barcelona and Athletic Bilbao stars having played in Friday's Spanish Cup final.
That left the door open for the likes of Atletico Madrid's Adrian Lopez to state his case, and he didn't disappoint, heading the world champions into a 64th-minute lead.
Adrian was also instrumental in Spain's second goal 11 minutes later when he earned a penalty after being felled by Serbia captain Branislav Ivanovic, with the spot kick converted by Santi Cazorla.
Spain kick off their Group C campaign against Italy on June 10, followed by the Republic of Ireland on June 14 and wrapping up with Croatia on June 18.
Ireland saw off Bosnia 1-0 in Dublin while Portugal were held 0-0 in Leiria by Macedonia.
Denmark lost 3-1 to a young Brazil side, who are preparing for the London Olympics, in a friendly in Hamburg with Hulk scoring two of the Brazilians' goals.
Elsewhere Saturday, there were wins for tournament co-hosts Poland who beat Slovakia 1-0.
Croatia beat Estonia 3-1, the Czech Republic edged Israel 2-1 while 2004 champions Greece were held 1-1 by Slovenia.