Van de Zandschulp after his victory over Altmaier: "I'm very happy to have got away with it".
The Netherlands had to be patient, but they will be playing in the Davis Cup final for the first time.
Van de Zandschulp and Griekspoor came from behind to beat Germany in both singles matches.
Botic van de Zandschulp was the first player to put his team on the road to qualification, winning a wild contest against Daniel Altmaier (6-4, 6-7, 6-3).
Van de Zandschulp lost a tie-break of anthology which saw him win several match points.
Speaking to Punto De Break, the 80th player in the world reflected on his performance: "I can remember some matches I've lost in my career, but I've never had so many match points.
"In the end, I managed to win," he begins.
"There were so many times I could have closed the deal, but that's tennis too. Daniel pulled out all the stops when it mattered.
For a moment, I think it was at 8-7 in the tie-break, I didn't know what to do. It was my ninth match point.
I had no idea how to finish the point. I'm very happy to have come through it."
On Sunday, the Netherlands will have three matches at most to clinch their first ever Davis Cup title. That will be against Italy or Australia.