Marc Lieb led Brendon Hartley as Porsche locked out the top two spots in opening practice for the six hour race at the Nurburgring.
Lieb's table-topping time of 1 minute 41.703 seconds was less than five hundredths of a second behind.
Andrea Lotterer was third fastest in the #7 Audi, with the sister car in fourth while Anthony Davison was the fastest Toyota in fifth.
Alex Brundle was the fastest LMP2 runner for G-Drive, with James Calado setting hte GT Pro pace for AF Corse Ferrari. Pedro Lamy set the fastest GT Am time for Aston Martin