Spielberg, Austria - Formula One points leader Nico Rosberg showed he remained the man to beat by setting the fastest lap in Friday's first free practice session ahead of Sunday's Austrian Grand Prix.
Rosberg lapped the 4.3km Red Bull Ring in 1m11.295s, 0.140sec faster than Mercedes team-mate Lewis Hamilton and 0.311sec ahead of double former champion Fernando Alonso.
Hamilton initially set the pace but Rosberg quickly showed he was at ease on the historic Spielberg circuit, coming off after just 19 laps, while the Briton completed 32.
Although racing at home, Red Bull's four-time champion Sebastian Vettel and Canadian Grand Prix winner Daniel Ricciardo struggled under an overcast sky and amid light rainy conditions.
Ricciardo set the 13th fastest lap, 1.275sec behind Rosberg, while Vettel had to settle for 15th at 1.693.
Friday's free practice was the drivers' first real opportunity to get to know the track and gather information ahead of Sunday's race.
The last time Spielberg hosted a Formula One Grand Prix was in 2003.
But drivers have insisted this initial lack of knowledge will hardly matter once the first free practice is done and dusted.
The tricky last turn leading into the final straight proved especially challenging, with Vettel briefly spinning off after going wide in the corner, while Ricciardo also bit into the side of the track.
But the first practice was probably most disappointing for Caterham's Marcus Ericsson and Adrian Sutil of Sauber, whose session ended prematurely as their cars encountered technical problems.
“It's like the car just kind of switched itself off coming out of Turn 1,” Caterham quoted Ericsson in a tweet, after the driver saw his car lifted off the track having completed just eight laps.
Sutil got one more lap in but “due to a broken hose, the turbo in Adrian Sutil's car does not work properly. He cannot get out again”, Sauber said.
Mercedes is looking to prove it has put its power problems from Montreal behind it and to keep a resurgent Red Bull at bay.
1 Nico Rosberg (Germany) Mercedes - 1m11.295 s
2 Lewis Hamilton (Britain) Mercedes - 1:11.435
3 Fernando Alonso (Spain) Ferrari - 1:11.606
4 Felipe Massa (Brazil) Williams - 1:11.756
5 Jenson Button (Britain) McLaren - 1:11.839
6 Sergio Perez (Mexico) Force India - 1:12.009
7 Nico Hulkenberg (Germany) Force India - 1:12.072
8 Valtteri Bottas (Finland) Williams - 1:12.114
9 Kevin Magnussen (Denmark) McLaren - 1:12.313
10 Jean-Eric Vergne (France) Toro Rosso - 1:12.364
11 Kimi Raikkonen (Finland) Ferrari - 1:12.365
12 Daniil Kvyat (Russia) Toro Rosso - 1:12.372
13 Daniel Ricciardo (Australia) Red Bull - 1:12.570
14 Esteban Gutierrez (Mexico) Sauber - 1:12.984
15 Sebastian Vettel (Germany) Red Bull - 1:12.988
16 Romain Grosjean (France) Lotus - 1:13.168
17 Pastor Maldonado (Venezuela) Lotus - 1:13.642
18 Jules Bianchi (France) Marussia - 1:13.738
19 Max Chilton (Britain) Marussia - 1:13.857
20 Kamui Kobayashi (Japan) Caterham - 1:14.611
21 Adrian Sutil (Germany) Sauber - 1:14.691
22 Marcus Ericsson (Sweden) Caterham - 1:17.501