Red Bull driver Mark Webber drove the quickest time in the first practice ahead of Sunday's Malaysian Grand Prix, edging Lotus driver Kimi Raikkonen as the Australian looks for his first victory in more than six months.
Webber, who finished a disappointing sixth at the season-opening Australian Grand Prix last week, outpaced Melbourne-winner Raikkonen by 0.068 seconds. The Finn was followed by reigning world champion teammate Sebastian Vettel of Red Bull who was 0.169 seconds off the pace.
Ferrari's Fernando Alonso was fourth fastest, while his teammate Felipe Massa had to settle for seventh.
Several other big names, however, struggled amid the hot and humid conditions.
Lewis Hamilton ended up 9th for Mercedes, while Jenson Button's McLaren continued its poor form ending up 11th.