Just as it looked like both sides would be settling for a point in the Group A opener, an attempted header from Janmaat to Jasper Cillessen saw the ball strike the post, and allowed Vaclav Pilar to tap home from close range in stoppage time.
"Yes, that's right. This is my fault and it is inexcusable," the Newcastle United full-back told NOS when asked whether he felt that he was to blame for the defeat.
"It was a big mistake, I wanted to head the ball back to Jasper, but I didn't hit it well. Now I've scored a sort of own goal and feel very bad about it. It felt like the ground had been swept away underneath me. Czech Republic away isn't easy, but we had to win this one."