Alonso was still in pain long after the final whistle and fears he may have broken a rib.
Clearly, the 28-year-old was not impressed by De Jong's conduct.
"It was one of the worst tackles I have ever suffered," he said.
"It was a tight game, there was respect from both sides and they had to close us down.
"But that challenge was really hard. It was one of the most painful tackles in my life and it was hard to play on.
"I have probably broken a rib, although I am not too worried about that."
Reigning European champion
No country has ever managed three on the trot, which will be
Alonso accepts there is plenty of work ahead of his team-mates before then but the raw talent is certainly there.
"Right now is not the time to think about the future, but of course the basics are there with this team," he said.
"The style is there, the mentality is there and the team spirit is there.
"If we keep working in this way many more big things may come."