Lewis Hamilton dominated the opening day of practice for the Austrian Grand Prix, outpacing Formula 1 title rival Nico Rosberg by almost four tenths of a second.
Hamilton was fastest early in the session while all drivers were running on the slower soft-compound Pirelli tyres, just 39-thousandths of a second faster than his Mercedes team-mate.
But when the pair headed out for their super-soft runs, Hamilton made a big improvement to put in a time 0.747s seconds faster than Rosberg, who found only a tenth on his first flier.
Hamilton subsequently found another tenth to improve his advantage to 0.857s briefly, only for Rosberg to string together a better lap to end up 0.377s down.
Later in the session, Hamilton did have some trouble while doing long-run work, complaining of a loss of power.
Ferrari driver Fernando Alonso was third fastest, just over nine tenths off the pace, while Williams driver Valtteri Bottas, who had been the closest challenger to Mercedes on soft-tyre pace, was fourth.
Felipe Massa completed a strong showing for Williams with fifth overall, just two-thousandths slower than his team-mate.
Sebastian Vettel, who started the session late thanks to his floor having to be changed after his high-speed spin exiting the final corner during the morning session, was sixth fastest, almost 1.3s slower than Hamilton.
Jenson Button, driving the updated McLaren, was seventh fastest, just six thousandths of a second slower than Vettel and a tenth quicker than the other Red Bull of Daniel Ricciardo, who also had to have a floor changed after a morning off.
Kevin Magnussen was ninth fastest, with Jean-Eric Vergne once again making it into the top 10 for Scuderia Toro Rosso.
It was a difficult session for Kimi Raikkonen, who ended up 11th fastest, half-a-second slower than team-mate Alonso, and endured a grassy moment after running wide at the last corner late on.
Adrian Sutil, who managed only nine laps this morning after a split hose led to the turbo failing, completed a full programme to end up 16th fastest.
Caterham driver Marcus Ericsson also had a better session after stopping after eight laps this morning.
Although rain threatened late in the session, it stayed away and teams were able to complete their planned programmes.
Pos Driver Team Time Gap Laps
1. Lewis Hamilton Mercedes 1m09.542s 37
2. Nico Rosberg Mercedes 1m09.919s +0.377s 50
3. Fernando Alonso Ferrari 1m10.470s +0.928s 40
4. Valtteri Bottas Williams-Mercedes 1m10.519s +0.977s 44
5. Felipe Massa Williams-Mercedes 1m10.521s +0.979s 39
6. Sebastian Vettel Red Bull-Renault 1m10.807s +1.265s 39
7. Jenson Button McLaren-Mercedes 1m10.813s +1.271s 44
8. Daniel Ricciardo Red Bull-Renault 1m10.920s +1.378s 36
9. Kevin Magnussen McLaren-Mercedes 1m10.936s +1.394s 45
10. Jean-Eric Vergne Toro Rosso-Renault 1m10.972s +1.430s 39
11. Kimi Raikkonen Ferrari 1m10.974s +1.432s 45
12. Daniil Kvyat Toro Rosso-Renault 1m11.261s +1.719s 45
13. Sergio Perez Force India-Mercedes 1m11.296s +1.754s 36
14. Esteban Gutierrez Sauber-Ferrari 1m11.491s +1.949s 42
15. Pastor Maldonado Lotus-Renault 1m11.765s +2.223s 30
16. Adrian Sutil Sauber-Ferrari 1m11.806s +2.264s 42
17. Nico Hulkenberg Force India-Mercedes 1m11.935s +2.393s 39
18. Max Chilton Marussia-Ferrari 1m12.229s +2.687s 43
19. Romain Grosjean Lotus-Renault 1m12.262s +2.720s 46
20. Jules Bianchi Marussia-Ferrari 1m12.279s +2.737s 36
21. Kamui Kobayashi Caterham-Renault 1m12.937s +3.395s 24
22. Marcus Ericsson Caterham-Renault 1m13.596s +4.054s 48