Briton Lewis Hamilton took first blood in his championship battle with Brazil's Felipe Massa at the Chinese Grand Prix by setting the quickest time in opening practice on Friday.
The 23-year-old McLaren driver, who could wrap up the title on Sunday, swept around the 5.451km circuit in one minute 35.630 seconds and clocked the two quickest times of the morning.
Ferrari's Massa, who trails Hamilton by five points and will be hoping to take the title race to the final race of the season in Sao Paolo, was second quickest in 1.36.020, nearly four tenths of a second behind Hamilton.
World champion Kimi Raikkonen, whose interest in the drivers' championship is over, was third quickest for Ferrari in 1.36.052 ahead of his fellow Finn Heikki Kovalainen in the other McLaren, who clocked 1.36.103.
Pole Robert Kubica, the only other driver left in the title race, showed what a struggle it will be to make up 12 points on Hamilton in the last two races as he was only able to manage the fifth fastest time of 1:36.507 for BMW-Sauber.
Spain's Fernando Alonso, who has won the last two races, continued his revival of fortunes with Renault by clocking the sixth fastest time (1:36.661).
Hamilton showed no signs of being distracted by the continuing controversy over the safety of his driving, although he did run off the track on his sixth lap halfway through the session.
He recovered immediately to top the time sheets on his seventh circuit and, although he was quickly trumped by Massa, his 11th lap saw him become the first driver to dip under 1.36 and he bettered even that on his 15th lap.
Hamilton, who was on pole as he chased the title in Shanghai last year but failed to finish the race, has been the subject of several complaints from his fellow drivers about unsafe driving at last week's Japanese Grand Prix.