The English 'dream team' of Littler and Humphries were tipped to win the tournament, but have been dumped out at the first hurdle in Stuttgart.
Schindler and Pietreczko - roared on by the home crowd - stormed to a sensational 8-4 victory over the world’s top two players to continue their bid for World Cup glory at the Eissporthalle.
There was nothing to separate the teams after four legs, but a terrific five-leg burst from the German duo catapulted them to the brink of victory at 7-2 - with World Cup debutant Pietreczko taking centre stage.
The 30-year-old landed nerveless 106 and 101 finishes during this spell, before fending off a late rally from Humphries and Littler to seal the deal with a clinical 62 combination.
“We believed in ourselves, and that was the key,” said Schindler. “The double 16s from Ricardo when it mattered just went in, so we’re really happy.
“This is a big win for us. German darts is in good shape right now, and we’re pushing forward as much as we can.”
Earlier, Scotland were whitewashed by the Netherlands, Wales beat the Philippines 8-2, Northern Ireland overcame South Africa and Ireland defeated Switzerland.
“It’s a great start. We did a job tonight, and that’s all that counts,” said Welsh number one Jonny Clayton.
“When you get to this stage of the tournament, every game is tough, but we’re confident in our game.
“We’re here to win (the World Cup of Darts) and we (Clayton and Gerwyn Price) always play well together, so look out!"
In the quarter-finals, new bookies' favourites Wales will take on Hong Kong and the Irish teams will face-off.
The other quarters will see the Netherlands test themselves against Czechia and Germany against Australia.