Heikki Kovalainen of McLaren-Mercedes was fastest in rain-effected free practice for the Japanese Grand Prix at Suzuka on Friday with championship leader Jenson Button deciding against racing in the second session.

Kovalainen’s time of 1 minute 40.356 seconds for the 5.807-kilometre circuit came in the first session, while Force India’s Adrian Sutil clocked the quickest time of 1:47.261 for the second session, which was reduced to just 13 minutes because of the weather.

Japanese Williams-Toyota driver Kazuki Nakajima was second-fastest in the morning session, 0.292 seconds behind Kovalainen, with Sutil third.

Brawn GP driver Button managed just 18th spot in the morning and sat out the final session like teammate and closest rival Rubens Barrichello.

Red Bull’s Sebastian Vettel was second quickest in the afternoon, followed by Vitantonio Liuzzi in the second Force India car.

Button can win the drivers’ championship this weekend if he manages to secure five more points than Barrichello.

German driver Timo Glock of Toyota hat to sit out the practice session owing to a fever and a heavy cold and was replaced by Japanese test driver Kamui Kobayashi. The Toyota team doctors said the driver would be able to participate in Saturday’s qualifying session.

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