MELBOURNE, Australia (AP) Reigning Formula One world champion Lewis Hamilton set the fastest time while his Mercedes teammate Nico Rosberg crashed out during wet Friday practice for the season-opening Australian Grand Prix.
Heavy morning rain and showers throughout the day meant there was very little useful running in terms of preparation for Saturday's qualifying and Sunday's race, which are expected to be dry.
Hamilton set the fastest time in opening practice when there was a small window of dry-weather tire use, and was quickest again in the second practice when only the intermediate and wet-weather tires were used.
Rosberg crashed out in the second session, when his car aquaplaned on surface water and hit a concrete barrier, knocking off the Mercedes' newly designed high-tech front wing and prematurely ending his day.
Rosberg became the first victim of the sport's new radio rules which outlaw a lot of radio communication between pit and driver so as to make drivers make their own judgments. Team principal Toto Wolff said the team was watching on monitors how the car was behaving on the wet track and decided the intermediate tire was not providing enough grip and he should change to full wet tires, but could not tell him before the accident occurred.
''We were debating if it was wet or heavy wet weather and in the end we decided it was heavy wet, but we couldn't tell him because of the new rules,'' Wolff said.
The few laps of opening practice which allowed dry tire running were more indicative of true pace than the times in the wetter second practice.
In that opening practice, Hamilton's time was four tenths of a second faster than Daniil Kvyat, and the Russian's Red Bull teammate and local favorite Daniel Ricciardo was third fastest.
McLaren had two cars in the top 10, giving a limited indication that the team could improve on its disappointing 2015, which was the first year back in the sport for engine supplier Honda.
Force India and Toro Rosso also set good times, suggesting they will live up to predictions of strong performances in the early part of the year.
Ferrari's Sebastian Vettel set no time in opening practice but was eighth fastest in the second, while teammate Kimi Raikkonen was third quickest overall.
Qualifying on Saturday, and Sunday's race, were both expected to be dry, so there was little useful data to be compiled from running in the wet on Friday. It meant qualifying was likely to be highly unpredictable, as no teams had been able to finalize their settings or decide which of the three available tire compounds would work best or how long they would last.
Teams and drivers will also have to adjust to a new qualifying format in which all drivers will get a few minutes in each of the three qualifying segments in which to set a time before the slowest driver will be eliminated every 90 seconds.