Maro Engel was quickest in another rain-filled session at Suzuka, with GruppeM Racing topping the time charts in Free Practice 1.
The German reeled off a 2:13.117 early in the two-hour session, which was hampered by several heavy downpours.
A heavy shower near the end of the first hour led all cars parked for nearly 30 minutes before conditions slightly improved.
Engel’s time was 0.087 seconds quicker than the No. 77 Craft-Bamboo Racing entry, which made it a Mercedes-AMG GT3 1-2 sweep.
The No. 25 Team WRT Audi R8 LMS GT3 Evo was third quickest, followed by the No. 44 Strakka Racing Mercedes in fourth and the GT3 Pro-Am class pace-setting No. 60 LM corsa Porsche 911 GT3 R in fifth.
A 90-minute night practice session is scheduled to get underway at 6:30 p.m. local time.
All drivers are required to complete at least one lap in darkness during the session.
RESULTS: Free Practice 1