Lewis Hamilton got his potentially decisive Chinese Grand Prix weekend off to an encouraging start by topping the first practice session in Shanghai.
The McLaren driver's title rival Felipe Massa was second for Ferrari, but was 0.390 seconds slower than Hamilton, who could potentially wrap up the 2008 championship this weekend, but arrives at the circuit under pressure following the controversial incidents and penalties of the Japanese Grand Prix.
Kimi Raikkonen (Ferrari) and Heikki Kovalainen (McLaren) completed the top four, with outside title contender Robert Kubica fifth for BMW ahead of the in-form Fernando Alonso (Renault).
After a very quiet start to the session, Raikkonen was the first of the major contenders to show his hand after 35 minutes, beating previous pace-setter Sebastien Bourdais by six tenths of a second, only to then spin at Turn 2 on his next lap.
The McLaren and Ferrari drivers then proceeded to swap the top spot repeatedly during a frantic 10 minutes which saw first Kovalainen, then Massa hit the front, before Raikkonen moved back ahead - but only for a few moments as Kovalainen also improved and returned to first position just after Raikkonen.
Hamilton took time to get up to speed, wasting one lap by running very wide over the run-off exiting Turn 13. But as the session hit its halfway point he produced a 1:36.044 with his first clean lap and moved to the head of the order.
Massa was still improving though, and two minutes later he usurped his title rival by 0.020 seconds.
That proved to be the final change of the first runs, but when the front-runners returned to the track 15 minutes later it was Hamilton who took charge. While his main rivals failed to improve their times, the championship leader found a further four tenths of a second and moved clear of the field with a 1:35.630 lap.
With the lead drivers all sticking to old tyres and relatively long runs in the closing minutes, Hamilton's time remained the benchmark through to the end of the morning.
Behind the top six, Kubica's teammate Nick Heidfeld took seventh, with Toro Rosso duo Sebastien Bourdais and Sebastian Vettel eighth and 10th, sandwiching Nelson Piquet (Renault).
The Turn 11/12 chicane was the scene of most of the session's incidents, with both Jarno Trulli (Toyota) and Mark Webber (Red Bull) having half-spins mid-corner - Trulli's leaving him briefly stuck on the grass until he found reverse and edged back onto the circuit. Honda's Rubens Barrichello also had a brief moment at this spot and bounced over the grass.
Piquet had an excursion through the pitlane gravel trap made famous by Hamilton's error in the 2007 race. Unlike Hamilton last year, though, Piquet was able to keep going through the gravel and return to his pit.
Pos Driver Team Time Laps 1. Hamilton McLaren-Mercedes (B) 1:35.630 23 2. Massa Ferrari (B) 1:36.020 + 0.390 24 3. Raikkonen Ferrari (B) 1:36.052 + 0.422 23 4. Kovalainen McLaren-Mercedes (B) 1:36.103 + 0.473 21 5. Kubica BMW Sauber (B) 1:36.507 + 0.877 25 6. Alonso Renault (B) 1:36.661 + 1.031 25 7. Heidfeld BMW Sauber (B) 1:37.040 + 1.410 23 8. Bourdais Toro Rosso-Ferrari (B) 1:37.070 + 1.440 32 9. Piquet Renault (B) 1:37.180 + 1.550 30 10. Vettel Toro Rosso-Ferrari (B) 1:37.278 + 1.648 25 11. Webber Red Bull-Renault (B) 1:37.491 + 1.861 26 12. Button Honda (B) 1:37.619 + 1.989 25 13. Nakajima Williams-Toyota (B) 1:37.630 + 2.000 23 14. Coulthard Red Bull-Renault (B) 1:37.638 + 2.008 22 15. Rosberg Williams-Toyota (B) 1:37.638 + 2.008 26 16. Glock Toyota (B) 1:37.664 + 2.034 29 17. Barrichello Honda (B) 1:37.827 + 2.197 28 18. Trulli Toyota (B) 1:38.219 + 2.589 24 19. Sutil Force India-Ferrari (B) 1:38.285 + 2.655 25 20. Fisichella Force India-Ferrari (B) 1:38.479 + 2.849 26 All timing unofficial