World championship leader Nico Rosberg ended the opening day of practice for the Formula One Japanese Grand Prix in a strong position after setting the pace in both sessions on Friday.
The German set his fastest time of one minute, 32.250 seconds on an overcast afternoon in Suzuka in the second of Friday's two sessions, after also having topped the timesheets at the end of the morning's opening 90-minutes of running.
Rosberg's Mercedes team-mate Lewis Hamilton was second in both and while the Briton was 0.214 seconds off his title-rival's pace in the morning he closed the gap to just 0.072 seconds in the second session.
Rosberg extended his advantage over Hamilton to 23 points in the overall standings after the reigning champion was forced to retire 16 laps from the finish while holding a comfortable lead during the last race in Malaysia.
Hamilton heads into Sunday's Japanese round desperately needing to revive his title hopes by clinching a third successive win at the Suzuka circuit.
Their Mercedes team could also wrap up their third successive constructors' crown on Sunday.
Kimi Raikkonen ended third-fastest for Ferrari, 0.323 seconds off Rosberg's pace. The Finn had been fourth-quickest in the morning behind team-mate Sebastian Vettel, who was fifth fastest in the second session.
Vettel heads into the weekend carrying a three-place grid penalty for tipping Rosberg into a spin in Malaysia.
Max Verstappen, sixth in the morning, split the two scarlet cars in fourth.
His team-mate Daniel Ricciardo who inherited the win in Malaysia after Hamilton retired, fell to 12th in the second session from fifth earlier after he was forced to abandon his flying lap when the virtual safety car was deployed after Esteban Gutierrez ground to a halt by the side of the track.
Force India, locked in a battle for fourth in the overall standings with Williams, continued to show a strong turn of speed.
Mexican Sergio Perez went sixth fastest ahead of German Nico Hulkenberg with the duo having set the seventh and eighth-fastest times in the morning.
Fernando Alonso, who survived an encounter with the barriers after losing control of his car at the fast Spoon corner early in the first session, ended the day eighth.