Lewis Hamilton set the pace in practice for the Malaysian Grand Prix.
The McLaren driver was fastest in both of Friday's practice sessions.
See hi-res Sepang practice pictures
However, both Hamilton and team-mate Jenson Button complained about the car's balance on the softer, option tyre, suggesting McLaren may not be race favourites.
Red Bull's Sebastian Vettel set the second quickest time, but his team-mate Mark Webber wasr forced to park his car in the gravel after less than half an hour. The team suspects an engine failure.
Mercedes finished the session with its cars third and fifth, sandwiching Button's McLaren. Nico Rosberg was quicker than Michael Schumacher.
1. Hamilton (McLaren-Mercedes) 1:34.1752. Vettel (Red Bull-Renault) +0.2663. Rosberg (Mercedes) +0.2684. Button (McLaren-Mercedes) +0.3635. Schumacher (Mercedes) +0.499 6. Kubica (Renault) +0.9737. Alonso (Ferrari) +1.4068. Buemi (Toro Rosso-Ferrari) +1.4859. Petrov (Renault) +1.69710. Sutil (Force India-Mercedes) +1.78211. Kobayashi (Sauber-Ferrari) +1.84312. Liuzzi (Force India-Mercedes) +2.04613. de la Rosa (Sauber-Ferrari) +2.15014. Alguersuari (Toro Rosso-Ferrari) + 2.15015. Massa (Ferrari) +2.42716. Barrichello (Williams-Cosworth) +2.63817. Hulkenberg (Williams-Cosworth) +3.24018. Trulli (Lotus-Cosworth) +4.27919. Kovalainen (Lotus-Cosworth) +4.355 20. Webber (Red Bull-Renault) +4.55821. Glock (Virgin-Cosworth) +4.88622. di Grassi (Virgin-Cosworth) +4.98323. Chandhok (HRT-Cosworth) +6.90924. Senna (HRT-Cosworth) +7.306
