Ferrari pair Felipe Massa and Kimi Raikkonen dominated first practice on Friday ahead of Sunday's Hungarian Grand Prix.
Massa set a fastest lap of one minute 20.981 seconds to finish ahead of Raikkonen as Ferrari bounced back from their disappointing performance in Germany.
Lewis Hamilton, winner of the last Grand Prix's, finished just behind his McLaren team-mate Heikki Kovalainen in fourth position.
Hamilton holds a four-point lead over his Massa in the drivers' championship.
Massa finished in third and Raikkonen down in sixth place at the last race and Ferrari launched an investigation to determine what went wrong.
The team determined the car was not at fault and their problems were a result of their drivers being unable to extract the maximum from the Bridgestone tyres.
But if the opening 90 minutes at Hungary are anything to go by, then Ferrari will represent a significant threat to Hamilton's bid for three successive victories.
Hamilton, who won this race last year, was 0.554 down on Brazilian Massa.
Timo Glock was sixth fastest, proving he is over his horrific smash in Hockenheim, while Britain's David Coulthard was 12th in his Red Bull - 1.719 seconds off Massa's pace.
Times from first practice session of the Hungarian Grand Prix:
1. Felipe Massa (Bra) Ferrari one min 20.981 secs
2. Kimi Raikkonen (Fin) Ferrari 1:21.345
3. Heikki Kovalainen (Fin) McLaren 1:21.410
4. Lewis Hamilton (GB) McLaren 1:21.535
5. Fernando Alonso (Spa) Renault 1:21.802
6. Timo Glock (Ger) Toyota 1:21.931
7. Robert Kubica (Pol) BMW Sauber 1:22.267
8. Nelson Piquet (Bra) Renault 1:22.326
9. Nick Heidfeld (Ger) BMW Sauber 1:22.370
10. Jarno Trulli (Ita) Toyota 1:22.457
11. Mark Webber (Aus) RedBull - Renault 1:22.654
12. David Coulthard (GB) RedBull - Renault 1:22.700
13. Sebastien Bourdais (Fra) Toro Rosso - Ferrari 1:22.900
14. Jenson Button (GB) Honda 1:22.917
15. Rubens Barrichello (Bra) Honda 1:23.093
16. Nico Rosberg (Ger) Williams - Toyota 1:23.147
17. Kazuki Nakajima (Jpn) Williams - Toyota 1:23.274
18. Adrian Sutil (Ger) Force India - Ferrari 1:23.353
19. Giancarlo Fisichella (Ita) Force India - Ferrari 1:23.459
20. Sebastian Vettel (Ger) Toro Rosso - Ferrari 1:23.923