Amsterdam: Bulgaria surprised the Netherlands 2-1 on Saturday in a friendly that showed the World Cup runners-up are struggling to find their trademark fluency ahead of the European Championship.
Substitute Ilian Micanski scored the winning header in injury time.
Robin van Persie gave the Netherlands the lead on the stroke of half-time, running onto a pass over the Bulgaria defence by Wesley Sneijder and volleying home with his left foot for his 26th international goal.
Bulgaria hit back shortly after the break through an Ivelin Popov penalty after Rafael van der Vaart was adjudged to have handled the ball in the area while attempting a sliding block.
The match at Amsterdam Arena looked to be heading for a draw until Micanski popped up at the far post to head home Stanislav Manolev's cross three minutes into injury time.
"I don't think we played too bad in the first half. We had a lot of possession and scored a beautiful goal," Netherlands captain Mark van Bommel said. "In the second half we were too static. Our mistakes allowed them to be dangerous."
Valeri Bojinov went close to giving Bulgaria a shock lead five minutes from the break when he beat goalkeeper Tim Krul with a curling left-foot free kick, only to see the ball slam into the bar.
The close call appeared to shake the Netherlands into life and Van Persie's clinical finish put the Netherlands ahead seconds later.
But a contentious handball call after the break against Van der Vaart let Popov level the score from the penalty spot.
Coach Bert van Marwijk began with English Premier League topscorer Van Persie on the right flank and Bundesliga topscorer Klaas-Jan Huntelaar at centre-forward, but the potentially lethal pairing failed to threaten the packed Bulgaria defence early on.
Van Marwijk also gave a starting spot to 18-year-old debutant Jetro Willems at leftback, making him the second-youngest Dutch international after Gerald Vanenburg in 1982.
Willems was replaced by Stijn Schaars after just over an hour, as Van Marwijk continued to hunt for his best option on the left of his defence.
The Netherlands suffered a worrying early setback when centreback Joris Mathijsen limped off in just the 14th after appearing to hurt his left hamstring.
Arjen Robben came on as a late substitute, but failed to provide the spark the Dutch needed to seal the win. The closest he came was when he sprinted past one defender on the right wing and fell in the penalty area under the challenge of Nikolay Bodourov, but did not win a spot-kick.
The Netherlands take on Denmark, Portugal and Germany in Group B at Euro 2012, in a group made up of four teams in the top 10 of the FIFA rankings. Bulgaria did not qualify for the tournament in Poland and Ukraine.