Kimi Raikkonen is ready to prove his 20th career victory was no fluke this weekend, although he suffered problems in first practice ahead of Sunday's Malaysian Grand Prix.
Raikkonen, who took the chequered flag in the season-opening race in Australia five days ago, managed to split the Red Bulls at the top of the timesheet at the end of the opening 90-minute session at the Sepang International Circuit.
Mark Webber emerged quickest with a lap of one minute 36.935secs at a track where temperatures are the hottest faced by the teams this year at 32 degrees centigrade.
Raikkonen, however, had to wait until 30 minutes before the end of the session before opting to set his first timed lap, and was on the pace from the word go, but only after Lotus had been forced to replace his KERS battery. But straight away the 33-year-old slotted in behind Webber, finishing 0.068secs adrift of the Australian who finished a disappointing sixth in his home race on Sunday.
Webber, who started on the front row in Melbourne alongside world champion team-mate Sebastian Vettel, suffered an ECU failure prior to the installation lap that compromised his start and from which he failed to adequately recover.
Behind Webber and Raikkonen was Vettel - 0.169secs down - with the trio comfortably clear of the rest of the field led by Ferrari's Fernando Alonso, but with the Spaniard a further 0.2secs off the pace.
Nico Rosberg was the best of the Mercedes duo in fifth, but the German was 0.653secs adrift. Team-mate Lewis Hamilton was down in ninth, nine tenths of a second behind Webber. Hamilton, in particular, suffered issues with his rear tyres, at one point complaining they were destroyed, affecting his overall pace on a circuit where he has yet to win.
Sandwiched in between the Mercedes pair were Force India duo Adrian Sutil and Paul Di Resta in sixth and eighth, although the former damaged a front wing at one stage, with Felipe Massa in his Ferrari in seventh.
Romain Grosjean completed the top 10 in his Lotus, almost a second off of Webber, whilst there appears no relief for McLaren as Jenson Button and Sergio Perez were 11th and 13th respectively. In a car the team admitted in Melbourne they are yet to understand given the radical approach they have taken with its design, Button was 1.238secs down, with Perez a further 0.6secs behind.
Williams' Pastor Maldonado and Valtteri Bottas were 12th and 16th, with Sauber pairing Nico Hulkenberg and Esteban Gutierrez 14th and 15th. Marussia's Max Chilton brought up the rear in 22nd, 4.578secs down - but, more pertinently, half a second behind team-mate Jules Bianchi, who was 20th.