Sebastian Vettel beat Red Bull team-mate Mark Webber to top spot in an incident-strewn second Formula 1 practice session at Suzuka.
Lewis Hamilton and Fernando Alonso both had moments at the Degners - the latter doing well to save a spin without damage – while Kimi Raikkonen, Sergio Perez and Pastor Maldonado all suffered early exits after accidents.
Perez's off was the most dramatic: the Mexican clipped the astroturf on the entry to Spoon with his McLaren's rear right and was pitched sideways into a heavy collision with the barriers.
Williams driver Maldonado also hit the tyres – this time at Degner, just 12 minutes into the session - while Raikkonen lost the rear of his Lotus and ended up beached in the gravel at Dunlop 30 minutes from the session's end.
The Finn still ended the session fourth fastest, as the field collectively switched to long runs for the final third of the afternoon.
That put him just behind the lead Mercedes of Nico Rosberg, who was little more than a quarter of a second down on Vettel in third.
Raikkonen's team-mate Romain Grosjean was fifth fastest, fractions ahead of Hamilton, whose best lap on the medium compounds was spoiled when he ran wide exiting the Degners.
Alonso's spin was one of several lurid moments for the Spaniard, who must finish inside the top eight on Sunday if he is to prevent Vettel from clinching a fourth straight world championship crown this weekend.
The Spaniard could only manage 10th at the flag, behind Toro Rosso's Daniel Ricciardo, Ferrari team-mate Felipe Massa and McLaren's Jenson Button.
Esteban Gutierrez beat Jean-Eric Vergne and Sauber team-mate Nico Hulkenberg to 11th, with the trio covered by less than one tenth of a second.
Perez was 16th, while Maldonado hung on to 18th despite completing just six laps.
Charles Pic claimed rear-quartet honours, although Jules Bianchi's crash meant he was unable to participate in the session.