Eight-time German Grand Prix champion Marc Marquez (30) fell to 14th after crashing during Friday's rain-hit second practice with Italian Marco Bezzecchi (24) posting the fastest time.
The Spaniard had finished second in the morning practice behind France's Johan Zarco, but fell midway through the afternoon session, his bike hitting that of the Frenchman, splitting it in two.
Both riders escaped injury, with Zarco, who comes into Sunday's race on the back of two successive podiums, placing tenth.
Bezzecchi's time of 1:20:271 was the fastest lap of the day.
MotoGP 2023 leader Francesco Bagnaia finished the second practice in fourth, having come in eighth place in the morning session.
Marquez has done brilliantly at Sachsenring, winning all eight of his previous German GPs there.