Force India's Adrian Sutil was fastest in a rain-affected second practice session for the Japanese Grand Prix at Suzuka on Friday ahead of Red Bull's Sebastian Vettel.

The German driver, a noted wet-weather specialist, emerged on top after a frantic last 10 minutes of a session held mostly in appalling conditions.

His lap of 1 minute 47.261 seconds was six-tenths of a second quicker than compatriot Vettel, with Sutil's team-mate Vitantonio Liuzzi coming third.

Reigning world champion Lewis Hamilton of McLaren and local hero Kazuki Nakajima of Williams rounded out the top five.

Three drivers, including Brawn GP team-mates and main championship rivals Jenson Button and Rubens Barrichello, didn't even turn a wheel in the 90-minute session, opting to stay in their garage.

Button, who leads Barrichello by 15 points in the drivers' championship standings, needs to score five more points than his team-mate this weekend to secure his maiden F1 crown.

Vettel, who showed some of Red Bull's expected Suzuka pace late on Friday, is 25 points behind the Englishman in the title fight.

After Friday's first practice was held in dry conditions but on a track wet from early-morning rain, a deluge hit the circuit an hour before the afternoon session, and did not abate for the entire 90 minutes.

The first timed lap, by Jaime Alguersuari of Toro Rosso, came after well over an hour of inactivity, the gloom only temporarily broken when one team made a paper boat and sent it sailing down the river that was the pit lane.

Renault's Fernando Alonso, Alguersuari's teammate Sebastien Buemi, Nakajima and Hamilton all briefly led the session, which only really got going in the final 10 minutes.

Sutil's benchmark lap came inside the final 60 seconds, and he survived a wild ride across the run-off area while pushing hard on his next lap before returning to the pits.

Practice continues at Suzuka on Saturday morning ahead of qualifying in the afternoon, with more wet weather predicted, although Sunday's race is, at this stage, expected to be dry.