Red Bull's Mark Webber headed McLaren's Lewis Hamilton as practice set up a mouth-watering Japanese Grand Prix.
Michael Schumacher crashed out after losing control of his Mercedes at the Spoon curve, hitting a tyre barrier.
Red Bull's Sebastian Vettel and Ferrari's Fernando Alonso were in third and fifth, split by the impressive Force India of Nico Hulkenberg.
Lotus's Romain Grosjean was sixth, ahead of McLaren's Jenson Button.
"It has been quite a smooth day," said Hamilton. "I love this circuit, so it has been really great fun."
Force India's Paul di Resta crashed after just five minutes in the most dramatic of several incidents in the second session, also at the troublesome Spoon curve.
Paul Di Resta
“I just found myself with the right-hand wheels on the grass. Probably a bit of frustration with Kimi [Raikkonen's Lotus] getting in my way”
"I just found myself with the right-hand wheels on the grass," Di Resta said, "probably a bit of frustration with Kimi [Raikkonen's Lotus] getting in my way but that's no excuse.
"I was 0.6secs up on my lap from first practice, so it's annoying to go off. Hopefully it won't cost me too much tomorrow."
Spoon, a tricky double-apex left-hander, caught out Schumacher late in the session.
The German legend, who on Thursday announced
he would retire for a second time at the end of the season,
made exactly the same mistake as Di Resta. The only difference was that he hit the barriers backwards, while Di Resta went in forwards.
It was the worst moment of a difficult day for Mercedes, whose other driver Nico Rosberg had stopped at the end of the first session with an engine problem.
Sauber's Sergio Perez,
who will replace Hamilton at McLaren next season
following the Englishman's decision to move to Mercedes, narrowly avoided a similar incident when the Mexican also put two wheels on the grass on the entry to Spoon but managed to stay on the track.
His team-mate Kamui Kobayashi also had a heart-stopping moment when he ran wide in the high-speed Dunlop corner but managed to rejoin.
The litany of incidents underlined Suzuka's well deserved reputation as one of Formula 1's toughest tests, but there were no major incidents in the 90-minute session.
Lotus's Kimi Raikkonen,
third in the championship behind Alonso and Vettel,
lost most of the session after he was forced to stop after just 20 minutes because of a problem with his Kers power-boost system.
"Why is the Kers not working?" Raikkonen asked his team over the radio.
Japan GP Second Practice
1. Mark Webber - Red Bull 1:32.193
2. Lewis Hamilton - McLaren 1:32.707
3. Sebastian Vettel - Red Bull 1:32.836
4. Nico Hulkenberg - Force India 1:32.987
5. Fernando Alonso - Ferrari 1:33.093
6. Romain Grosjean - Lotus 1:33.107
7. Jenson Button - McLaren 1:33.349
8. Bruno Senna - Williams 1:32.499
9. Felipe Massa - Ferrari 1:32.614
10. Michael Schumacher - Mercedes 1:32.750
His engineer replied: "We have a Kers problem, we have to treat the car as unsafe at the moment."
Raikkonen returned to the pits and was only able to get out on to the track with a little over five minutes remaining.
Alonso arrived in Japan with a 29-point championship lead over Vettel, who is 16 points ahead of Raikkonen, with Hamilton a further seven adrift.
The Spaniard's Ferrari looked uncompetitive in the first session but he was much quicker in the second, setting the fastest time straight out of the pits, from Hamilton and Vettel.
"We can be reasonably happy," said Vettel. "The car seems to be improving. There are still some things we need to improve so we need to do another step overnight. Tomorrow it will be very close.
"We had a good day. This morning the car was very nervous but this afternoon seemed to be quite a bit better. I was a lot happier, and both [tyre] compounds we seemed to perform reasonably well."
"It looks pretty competitive at the front," said BBC F1 technical analyst Gary Anderson. "I'd like to pat Hulkenberg on the back - that's a good effort by him."
Both Ferrari and Red Bull had problems with blistering of their rear tyres - where the surface of the rubber overheats and bubbles.
Anderson said it looked like quite a serious problem on both cars.
But Vettel said he was not concerned about it.
Button on top in Suzuka practice 1
"Generally the track is quite hard for the tyres," he said, "because there are a lot of high-speed corners one after the other so there is no time of the tyre to rest. We did a lot of laps, at some stage it is natural the tyres start to go off and you start to slide around. But I think overall we can be quite happy."
It was unclear immediately whether McLaren were suffering similar problems, as they would be expected to if their main rivals were in such trouble.
Hamilton and Button were running different set-ups, with more downforce on Hamilton's car.
Button has a
five-place grid penalty as a result of a gearbox change
so extra straight-line speed will be valuable as he tries to make up places in the race.
In the closing seconds, Vitaly Petrov spun at the first corner after his rear wing tore off on the pit straight.
Japanese Grand Prix 2012, day two
- Saturday, 6 October: Third practice 02:55 BST; 5 live Sports Extra and live text online. Qualifying 05:55 BST; 5 live Sports Extra and live text commentary online. Highlights on BBC One 13:00 BST.
Japanese Grand Prix 2012, day three
- Sunday, 7 October: Race: 06:55 BST, 5 live and live text commentary online. Highlights on BBC One 14:05 BST and Mon 8 Oct at 00:35 BST.