Fernando Alonso set the pace in a truncated first practice at Austin when first fog held up proceedings and then the lack of a helicopter compounded the situation.
The start of first practice was delayed by 40 minutes due to heavy fog over the Circuit of the Americas with Race Control announcing that an hour-long session could kick off at 9:40am local time.
There was no time wasting from the drivers when the light turned green and new Lotus signing Heikki Kovalainen was the first out on track although it was Jenson Button's 1:41.934 that got the timesheets rolling.
While the McLaren driver put in the laps, Ferrari were working on Fernando Alonso's car which was up on jacks while his team drained the fluids - and all the while the Spaniard, whose back was taped up, sat in the car!
Back in the action, Button lowered the benchmark to a 1:39.493 ahead of Sergio Perez and Nico Hulkenberg only for the red flag to be thrown after just 15 minutes due to "further problems with the medical helicopter" which had not yet arrived at the track.
Although there was no chopper in sight, a cut-off time of 11am was set for the session with the clock counting down. It finally arrived with 32 minutes remaining, prompting a mad dash from the drivers who were in desperate need of track time.
Lap times came through thick and fast with Alonso jumping to third behind the McLarens and ahead of Daniel Ricciardo, Hulkenberg, Paul di Resta, Romain Grosjean and Felipe Massa.
Alonso was the first to jump the McLarens as he went quickest with a 1:38.767 with Valtteri Bottas following him up the order into second place ahead of Grosjean, Mark Webber and Hulkenberg.
Rodolfo Gonzalez became the first and only casualty of the session when he had an engine "blow-out" with three minutes left in the session. Disappointing and very short run for the Marussia test driver.
As the clock counted down, it was Alonso sitting in the P1 slot with a 1:38.343 with Button second, 0.028s down, and Bottas third, 0.045s off the pace.
Notably, Daniil Kvyat was 17th quickest, just 0.202s behind Daniel Ricciardo.
1 Fernando Alonso Ferrari 1:38.343 16 laps
02 Jenson Button McLaren 1:38.371 +0.028 25 laps
03 Valtteri Bottas Williams 1:38.388 +0.045 17 laps
04 Esteban Gutierrez Sauber 1:38.532 +0.189 18 laps
05 Nico Rosberg Mercedes 1:38.657 +0.314 21 laps
06 Lewis Hamilton Mercedes 1:38.979 +0.636 21 laps
07 Felipe Massa Ferrari 1:39.005 +0.662 16 laps
08 Mark Webber Red Bull 1:39.083 +0.740 17 laps
09 Nico Hulkenberg Sauber 1:39.158 +0.815 17 laps
10 Pastor Maldonado Williams 1:39.200 +0.857 15 laps
11 Romain Grosjean Lotus 1:39.238 +0.895 13 laps
12 Sergio Perez McLaren 1:39.256 +0.913 17 laps
13 Heikki Kovalainen Lotus 1:39.487 +1.144 18 laps
14 Adrian Sutil Force India 1:39.699 +1.356 15 laps
15 Paul di Resta Force India 1:39.836 +1.493 15 laps
16 Daniel Ricciardo Toro Rosso 1:39.863 +1.520 19 laps
17 Daniil Kvyat Toro Rosso 1:40.065 +1.722 20 laps
18 Sebastian Vettel Red Bull 1:40.662 +2.319 20 laps
19 Alexander Rossi Caterham 1:41.399 +3.056 21 laps
20 Max Chilton Marussia 1:41.605 +3.262 19 laps
21 Charles Pic Caterham 1:42.054 +3.711 19 laps
22 Rodolfo Gonzalez Marussia 1:43.716 +5.373 17 laps
Friday's Pictures From Austin