Nico Rosberg headed Mercedes team-mate Lewis Hamilton in a rain-affected first practice session at the Austrian Grand Prix.
He was 0.14 seconds clear of Hamilton, with Ferrari's Fernando Alonso third ahead of Williams' Felipe Massa.
In a session punctuated by incidents, including a spectacular double-spin by world champion Sebastian Vettel, Jenson Button took fifth for McLaren.
The Force Indias of Sergio Perez and Nico Hulkenberg were sixth and seventh.
The Red Bulls of Canadian Grand Prix winner Daniel Ricciardo and Vettel were only 13th and 15th. Alonso's team-mate Kimi Raikkonen was 11th, nearly 0.7secs down on the Spaniard.
There was intermittent rain through the session on a track which has only nine corners, but is an interesting and demanding mix of slow-speed and fast curves in a spectacular setting in the Styrian mountains.
The track proved difficult for the drivers, only a handful of which, including Rosberg and Vettel, had driven it in the junior categories. And only Alonso, Button, Massa and Kimi Raikkonen had previously taken part in an Austrian Grand Prix. The race was last held on this track, when it was called the A1-Ring, in 2003.
There were a number of off-track incidents as drivers learned the circuit, with many running wide, including Hamilton, Rosberg, Massa, Alonso and his Ferrari team-mate Kimi Raikkonen, and several other drivers.
The most spectacular by far was Vettel's spin. The world champion ran wide coming out of the final right-hander, over the kerb, on to the artificial grass beyond it and then spun twice in quick succession, somehow without hitting anything, when his car hit the grass.
BBC F1 analyst Allan McNish, watching at the final corner, said: "The Mercedes look very good. The Red Bulls are sharp into the apex but are struggling with a lack of power out of them, and the Ferraris look very stable.
"I expect this to be a good weekend for Williams if they can put qualifying and the race together, and I don't think we have seen everything from Red Bull. They tend to run with a lot of fuel in first practice."
Alonso was 0.311secs off Rosberg's pace and 0.15secs clear of Massa, but Ferrari always tend to show better than their true competitive position on Friday and the double world champion said he expected another difficult weekend for the team.
"This year we are definitely in a position we are not happy with," he said.
"Mercedes is dominating by a big margin and we are aware of this. We need to put in place some of the things we are weak at the moment, improve in different areas.
"We need to use Fridays to test experimental parts not just for this year but also for next year and we need to use the rest of this championship for preparation probably."