Red Bull's Mark Webber set the fastest time in Friday's opening practice session for the Formula One Malaysian Grand Prix, finishing more than 1.6 seconds clear of the rest of the field.
Webber, eager to make up for a disappointing performance in his home Australian Grand Prix and season opener, set a time well ahead of second-fastest Lewis Hamilton of McLaren and third-fastest Michael Schumacher of Mercedes.
Felipe Massa was the best of the Ferraris in sixth, ahead of Fernando Alonso in ninth, while defending champion and first race winner Sebastian Vettel of Red Bull was well down the timing sheets in 17th.
The session had some worrying wheel failures at high speed that affected both Renaults and a Virgin.
Renault's Nick Heidfeld had his right front permanently lock during the early part of the session and completed most of the lap with his undertray kicking up sparks. He'd set the seventh-best time before the incident.
The problems deepened for Renault when Vitaly Petrov's front left wheel and suspension exploded under braking, sending the Russian spearing over a gravel trap.
Virgin's Jerome d'Ambrosio suffered a similar failure on the front right side and also ran off into the gravel.
Narain Karthikeyan's engine gave way as he was exiting the pits early in the session, sending out a plume of smoke, but the Hispania driver did emerge in the final minutes to set a time.
However both Hispanias appear to be at risk of not qualifying for Sunday's race, as both Karthikeyan and Vitantonio Liuzzi's best times were more than 7 percent slower than Webber's time. They need to be within 7 percent of the best car in the first part of Saturday's qualifying or they can not race.
Force India reserve driver Nico Hulkenberg was an impressive fourth fastest, with Williams rookie Pastor Maldonado fifth. Williams veteran Rubens Barrichello was eighth and Mercedes' Nico Rosberg was tenth.
McLaren's Jenson Button was also well off the pace - 3.3 seconds slower than Webber - and complained of poor rear grip during the session.
There is a second practice session later on Friday, with qualifying on Saturday and the race Sunday.