Sebastian Vettel led Mark Webber in a Red Bull one-two as the United States Grand Prix weekend commenced properly in practice two.
Following the disjointed morning session hampered by both fog and a failed medical helicopter, the Formula 1 teams were able to get plenty of trouble-free running in the afternoon.
To little surprise, Vettel was the pacesetter for most of the session. He was swiftly down to a benchmark 1m38.211s lap on the hard tyre.
Although Nico Rosberg and Webber popped in front by switching to mediums sooner, Vettel's 1m37.305s on the softer rubber put him on top again.
Webber ended up 0.115 seconds slower in second, both Red Bulls having shown good long-run pace too.
Rosberg remained best of the rest in third, ahead of Mercedes team-mate Lewis Hamilton.
Lotus's new recruit Heikki Kovalainen managed to complete 41 laps as he got used to Kimi Raikkonen's former seat, and was an impressive fifth quickest. The Finn was 0.182s faster than team-mate Romain Grosjean in eighth.
Sauber had a strong day as Esteban Gutierrez repeated his rapid morning form in sixth, followed by team-mate Nico Hulkenberg.
Jenson Button's McLaren and Fernando Alonso's Ferrari completed the top 10.
Williams had been rapid in practice one, but Valtteri Bottas was only 16th in the second session, with team-mate Pastor Maldonado two places further back and quick to express his unhappiness via team radio.
Much of the final part of the session ran under yellow flags after Max Chilton went off at the last corner with what he suspected was a brake failure on his Marussia.
The tractor vehicle sent to recover the car got into some difficulty, before finally managing to clear the car away.
Pos Driver Team Time Gap Laps
1. Sebastian Vettel Red Bull-Renault 1m37.305s 35
2. Mark Webber Red Bull-Renault 1m37.420s +0.115s 37
3. Nico Rosberg Mercedes 1m37.785s +0.480s 38
4. Lewis Hamilton Mercedes 1m37.958s +0.653s 38
5. Heikki Kovalainen Lotus-Renault 1m38.073s +0.768s 41
6. Esteban Gutierrez Sauber-Ferrari 1m38.229s +0.924s 40
7. Nico Hulkenberg Sauber-Ferrari 1m38.254s +0.949s 40
8. Romain Grosjean Lotus-Renault 1m38.255s +0.950s 33
9. Jenson Button McLaren-Mercedes 1m38.269s +0.964s 34
10. Fernando Alonso Ferrari 1m38.461s +1.156s 33
11. Adrian Sutil Force India-Mercedes 1m38.719s +1.414s 31
12. Felipe Massa Ferrari 1m38.938s +1.633s 37
13. Sergio Perez McLaren-Mercedes 1m38.941s +1.636s 31
14. Daniel Ricciardo Toro Rosso-Ferrari 1m39.246s +1.941s 28
15. Paul di Resta Force India-Mercedes 1m39.410s +2.105s 34
16. Valtteri Bottas Williams-Renault 1m39.512s +2.207s 37
17. Jean-Eric Vergne Toro Rosso-Ferrari 1m39.579s +2.274s 36
18. Pastor Maldonado Williams-Renault 1m39.784s +2.479s 33
19. Charles Pic Caterham-Renault 1m40.376s +3.071s 39
20. Giedo van der Garde Caterham-Renault 1m40.563s +3.258s 35
21. Max Chilton Marussia-Cosworth 1m46.226s +8.921s 31
22. Jules Bianchi Marussia-Cosworth 1m47.009s +9.704s 20