Porsche's Brendon Hartley set the fastest lap during free practice for this weekend's 6 Hours of Fuji.
The Kiwi set a best of 1m24.480s in the #17 Porsche 919 Hybrid, as he and teammates Mark Webber and Timo Bernhard look to score a third successive WEC victory in Japan.
Hartley’s FP2 time was a fraction quicker than Audi man Andre Lotterer’s best effort from the slightly cooler opening session.
The German, who treats Japan as a second home after racing there for the last decade, set the quickest ever WEC lap of Fuji on a 1m24.497s - 1.8s faster than the previous best, which he had set in 2012.
Most of the teams were experimenting with different set-ups during the morning session, with Porsche evaluating body-kits in an effort to determine the best aero solution for the near-mile long straight and technical final sector.
With rain forecast for raceday on Sunday, teams also took the opportunity to throw on additional downforce and test grippier set-ups.
Romain Dumas looked set to eclipse team mate Hartley’s best effort in the afternoon, but his lap was compromised because of a red flag, as Scott Sharp stopped in his ESM Ligier.
As a result, the #18 Porsche 919 Hybrid had to settle for third, ahead of the other Audi R18 e-tron quattro crewed by Lucas Di Grassi, Oliver Jarvis and Loic Duval.
The only significant on-track incident during the day came in the morning session as Nick Leventis in the Strakka Racing Gibson was adjudged to have made contact with Loic Duval's Audi. Leventis was subsequently given a suspended stop/go penalty for the altercation.
Nelson Panciatici’s Signatech Alpine led LMP2 class in the morning, but his time of 1m32.701s was beaten by Sam Bird in the afternoon session.
The former Mercedes test driver set a series of fast laps around the 2.83-mile track, peaking with a 1m32.131s in the G-Drive Ligier-Nissan.
G-Drive’s title rivals KCMG placed second in the quicker afternoon session with Nick Tandy exploring the Fuji track for the first time and immediately showing good pace in the ORECA 05-Nissan.
The #92 Manthey Porsche and the Larbre Corvette topped the GTE-Pro and Am classes respectively in the first session, while Gianmaria Bruni showed his Ferrari's straight-line speed supremacy in the afternoon by leading home AF Corse teammate James Calado for a Maranello 1-2.
Stuart Hall made it a positive afternoon for AF Corse by claiming the top spot in LMGTE Am on a 1m40.706s lap.