Melbourne: McLaren driver Jenson Button set the fastest time in Friday's first practice session for Formula One's season-opening Australian Grand Prix, ahead of teammate Lewis Hamilton.
Button was a quarter of a second faster than Hamilton with Mercedes' Michael Schumacher and Ferrari's Fernando Alonso next on the timesheets.
Reigning world champion Sebastian Vettel was 11th, more than two seconds off the pace in his Red Bull. His teammate, local hope Mark Webber, fared better and was fifth fastest.
The track was wet from morning rain and much of the session was conducted on intermediate tires, but drivers were able to switch to the slick dry-weather tires for the final half hour.
Ferrari's Felipe Massa spun off the track into a gravel trap to prematurely end his session, but the first practice was otherwise free of incident.
Mercedes' Nico Rosberg was sixth fastest, and Toro Rosso's Daniel Ricciardo seventh in front of his home crowd. Williams' Pastor Maldonado had the eighth-fastest time, ahead of Lotus' Kimi Raikkonen, with Sauber's Kamui Kobayashi rounding out the top ten.
Raikkonen, back in Formula One after a two-year break, only emerged for his flying laps in the final 15 minutes of the session due to a steering problem on his Lotus.
The leading times set by the McLaren was testament to the more settled preseason campaign the team has enjoyed going into 2012, after the difficulties of the previous season when it had to overhaul its design just before the opening race.
Schumacher, still looking for his first podium position since his comeback to the sport, had reason for optimism after his third placing.
The legality of Mercedes' rear wing had been questioned by some rival teams, but was approved by the sport's governing body, the FIA. That leaves other teams having to play catch-up to come up with a similar design, which has slots on the underside of the wing to increase downforce without sacrificing straight-line speed.
The HRT team's start to the season lived down to expectations, having not been ready for any of the preseason testing sessions. Narain Karthikeyan ventured briefly on track before suffering a failure and coasting to a stop, while the car of Pedro de la Rosa was still being pieced together and took no part Friday.
The team could not take part in last season's Australian GP and will again face a struggle to qualify this year, as all cars must be within seven percent of the fastest time in qualifying in order to take part.
Marussia fared little better with Timo Glock more than seven seconds off the pace and rookie Charles Pic 12 seconds off Button's time.