Red Bull lived up to its status as pre-race favourite in opening practice at a dry and sunny Suzuka, with last year's Japanese Grand Prix winner Sebastian Vettel leading teammate Mark Webber in a comfortable 1-2.
But while two of the title contenders sat atop the times, another has already hit trouble, with Lewis Hamilton crashing heavily at Degner halfway through the session, costing the McLaren driver 45 minutes of track time on a day when the team has substantial upgrades to evaluate.
Hamilton's crash was a typical Degner incident, as he ran slightly wide at the first part of the fast, downhill double right-hander, then plowed through the gravel at the second element and mangled the car's left front against the barriers.
The Briton had been quickest for a short time prior to the crash, but moments before he hit the wall, he was deposed by Vettel's 1m33.157sec, half a second quicker than Hamilton's time, although the latter had set a new sector one benchmark on the lap that ended in the Degner wall.
Vettel would remain on top for the rest of the morning, raising his pace a few times to eventually reach a best of 1m32.585sec. He maintained a half-second cushion over the field for a long while, before Webber closed to within 0.048sec.
Hamilton's time kept him in fifth place, behind impressive performances from Renault's Robert Kubica and Force India's Adrian Sutil, but Jenson Button was only 12th in the second McLaren – and came very close to replicating his teammate's accident with two minutes to go. Button had a wild ride over the curb between the Degners then slid sideways into the gravel, but caught the car before reaching the wall.
Fernando Alonso had a low-key session, the Ferrari driver only 13th, two places behind his teammate Felipe Massa.
Williams made a strong start to the weekend with sixth and seventh places for Rubens Barrichello and Nico Hulkenberg, while Michael Schumacher was an encouraging eighth in the Mercedes. His teammate Nico Rosberg was 10th despite only completing nine laps and spending the second half of the session in the garage with his car receiving attention.
The two Mercedes were split by Sauber's Nick Heidfeld, with his teammate and home hero Kamui Kobayashi typically spectacular but only 14th.
Aside from the McLarens incidents, the only other notable excursion was a quick off at the hairpin by Toro Rosso's Jaime Alguersuari.
Heikki Kovalainen was quickest among the new teams in his Lotus, 0.3sec ahead of Virgin's Timo Glock, who was stuck in the garage for the first hour but was quick when his car was ready to take to the track. The team again ran Jerome d'Ambrosio in Lucas di Grassi's car, with the Belgian 0.4sec behind Glock in 22nd.
Pos Driver Car Time Gap Laps
1. Sebastian Vettel Red Bull-Renault 1m32.585s 23
2. Mark Webber Red Bull-Renault 1m32.633s + 0.048s 23
3. Robert Kubica Renault 1m33.129s + 0.544s 23
4. Adrian Sutil Force India-Mercedes 1m33.639s + 1.054s 13
5. Lewis Hamilton McLaren-Mercedes 1m33.643s + 1.058s 9
6. Rubens Barrichello Williams-Cosworth 1m33.677s + 1.092s 21
7. Nico Hulkenberg Williams-Cosworth 1m33.707s + 1.122s 24
8. Michael Schumacher Mercedes 1m33.739s + 1.154s 20
9. Nick Heidfeld Sauber-Ferrari 1m33.791s + 1.206s 23
10. Nico Rosberg Mercedes 1m33.831s + 1.246s 9
11. Felipe Massa Ferrari 1m33.929s + 1.344s 25
12. Jenson Button McLaren-Mercedes 1m34.042s + 1.457s 19
13. Fernando Alonso Ferrari 1m34.169s + 1.584s 23
14. Kamui Kobayashi Sauber-Ferrari 1m34.271s + 1.686s 19
15. Vitaly Petrov Renault 1m34.373s + 1.788s 24
16. Vitantonio Liuzzi Force India-Mercedes 1m34.379s + 1.794s 21
17. Sebastien Buemi Toro Rosso-Ferrari 1m34.991s + 2.406s 26
18. Jaime Alguersuari Toro Rosso-Ferrari 1m35.684s + 3.099s 22
19. Heikki Kovalainen Lotus-Cosworth 1m36.949s + 4.364s 25
20. Timo Glock Virgin-Cosworth 1m37.329s + 4.744s 17
21. Jarno Trulli Lotus-Cosworth 1m37.388s + 4.803s 23
22. Jerome D'Ambrosio Virgin-Cosworth 1m37.778s + 5.193s 23
23. Bruno Senna Hispania-Cosworth 1m38.814s + 6.229s 28
24. Sakon Yamamoto Hispania-Cosworth 1m39.443s + 6.858s 26
All timing unofficial